GNU-Darwin Web
"http://www.w3.org/TR/REC-html40/loose.dtd">

# TTH: a TEX to HTML'' translator.

 Version 2.78

## Abstract

TTH translates TEX documents that use the Plain macro package or LATEX, into HTML. It is extremely fast and completely portable. It produces web documents that are more compact and managable, and faster-viewing, than those from other converters, because it really translates the equations, instead of converting them into images.

# Contents

1  Capabilities
1.1  Plain TEX
1.1.1  Mathematics
1.1.2  Formatting and Macro Support
1.2  LATEX
1.2.1  Environments:
1.2.2  LATEX Commands:
1.3  Special TEX usage for TTH
1.4  Unsupported Commands
2  Installation
3  Usage
4  Messages
5  Mathematics
5.1  Equations
5.2  In-line Equation Limitations
6  Features dependent on external programs.
6.1  Independence of [La]TEX installation and the -L switch.
6.2  BibTEX bibliographies
6.3  Indexing
6.4  Graphics Inclusion: epsfbox/includegraphics
6.5  Picture Environments
7  Tabular Environment or Halign for Tables
7.1  Tabular
7.2  Halign
7.3  Longtables
8  Boxes, Dimensions, and fills
9  TEX command definitions and other extensions
9.1  Delimited-parameter macros and Conditionals
9.2  Macro- and Style-file inclusion
9.3  Layout to include arguments of unknown commands
9.4  Restrictions on redefinition of internal commands
9.4.1  Footnotes
10  Color
10.1  LATEX Color
10.2  Plain Color
10.3  Limitations
11  HTML and output
11.1  Formal HTML validation
11.2  HTML Styles
12  Browser Problems
12.1  MacIntosh browser font problems
12.2  Netscape Composer
12.3  X font problems
12.4  Internet Expl*der
12.5  Printing
12.6  Other Browser Bugs
12.7  Cascading Style Sheets and Unicode
13  Code Critique
15  Acknowledgements
A  Appendix: Non-Standard TEX Macros
Index

## 1  Capabilities

### 1.1  Plain TEX

#### 1.1.1  Mathematics

Almost all of TEX's mathematics is supported with the exception of a few obscure symbols that are absent from the fonts normally available to browsers. Support includes, for example, in-line equations with subscripts and superscripts, display equations with built-up fractions, over accents, large delimiters, operators with limits; matrix, pmatrix, cases, [but not bordermatrix]; over/underbrace [but using a rule, not a brace].

#### 1.1.2  Formatting and Macro Support

• Font styles: \it, \bf, \sl, \uppercase, everywhere, \rm in equations1.
• Accented characters written like \"o or \'{e}.
• Guess the intent of font definitions, i.e. \font commands [optionally, remove contruct].
• Macro definitions that are global: \gdef, \xdef, \global\def, \global\edef; or local to the current group: \def, \edef.
• Definitions with delimited arguments.
• Input of files [see 9.2].
• Newcount, number, advance and counter setting [global counter setting only].
• Conditionals: iftrue, iffalse, ifnum, ifodd, ifcase, if [for defined commands and plain characters, not some internals] 2, ifx [only for defined commands and counters; internals appear undefined], ifvmode, ifmmode, newif.
• Centerline, beginsection, item, itemitem, obeylines; hang, hangindent, narrower [for entire paragraphs, hangafter ignored]. Headline is made into a title, footnote{}{}. Comments: removed.
• Tables: halign [uses border style if the template contains vrule.]. Settabs, \+.
• Simple uses of \hbox,\vbox and \hsize to align text and make boxes with restricted widths, but these are discouraged.

### 1.2  LATEX

LATEX support includes essentially all mathematics plus the following

#### 1.2.1  Environments:

em, verbatim, center, flushright, verse, quotation, quote, itemize, enumerate, description, list [treated as if description], figure, table, tabular[*,x], equation, displaymath, eqnarray, math, array [not generally in in-line equations], thebibliography, [raw]html, index [as description], minipage [ignoring optional argument], longtable [but see 7.3].

#### 1.2.2  LATEX Commands:

[re]newcommand, newenvironment, chapter, section, subsection, subsubsection, caption, label, ref, pageref [no number], emph, textit, texttt, textbf, centering, raggedleft, includegraphics, [e]psfig, title, author, date [maketitle ignored: title etc inserted when defined], lefteqn, frac, tableofcontents, input, include [as input, includeonly ignored], textcolor, color, footnote [ignoring optional arg], cite, bibitem, bibliography, tiny ... normalsize ... Huge, newcounter, setcounter, addtocounter, value [inside set or addto counter], arabic, the, stepcounter, newline, verb[*] [can't use @ as separator], bfseries, itshape, ttfamily, textsc, ensuremath, listoftables, listoffigures, newtheorem [no optional arguments permitted], today, printindex, boldmath, unboldmath, newfont, thanks, makeindex, index, @addtoreset, verbatiminput, paragraph, subparagraph, url, makebox, framebox, mbox, fbox, parbox [ignoring optional argument], definecolor, colorbox, fcolorbox [not in equations], pagecolor [discouraged], savebox, sbox, usebox.

These cover most of the vital LATEX constructs. Internal hypertext cross-references are automatically generated (e.g. by ref and tableofcontents) provided LATEX has previously been run on the document and the appropriate command-line switch is used.

### 1.3  Special TEX usage for TTH

A few non-standard TEX commands are supported as follows 3. See also 6.4.
\epsfbox{file.[e]ps} Puts in an anchor called "Figure" linked to
file.[e]ps (default), or alternatively calls user-supplied script
to convert the [e]ps file to a gif image and optionally inline it.
\special{html:"tags"} inserts tags'' into the HTML e.g. for images etc.
\href{reference}{anchor} highlights anchor'' with href=reference''.
\url{URL} like \href but with URL providing both reference and anchor.
\begin{[raw]html} ... \end{[raw]html} environment passed direct to output.
\tthdump{...} The group is omitted by tth. Define \tthdump as a nop for TeX.
%%tth:... The rest of the comment line is passed to tth (not TeX) for parsing.



### 1.4  Unsupported Commands

When TTH encounters TEX constructs that it cannot handle either because there is no HTML equivalent, or because it is not clever enough, it tries to remove the mess they would otherwise cause in the HTML code, generally giving a warning of the action if it is not sure what it is doing. The following are not translated.

 \magnification \magstep etc : Removes the whole construct.
New or non-standard dimension tokens: removed.
Some boxes in equations.
\raisebox, \lowerbox and similar usages.



## 2  Installation

The source for TTH is flex code which is processed to produce a C program tth.c which comprises the distribution. This file is compiled by

	gcc -o tth tth.c


or whatever C compiler you are using. Compilation takes a couple of minutes on a fast 486.

The executable should then be copied to whatever directory you want (preferably on your path of course). That's all!

Alternatively you may be able to obtain a precompiled executable from wherever you accessed this file. The Wind@ws executable comes with a batch file for installation. Just run it by the command install''.

## 3  Usage

Command line is as follows. The order of the parts is irrelevant. Switches (preceded by a minus sign -) can appear anywhere on the line. Square brackets should not be entered, they simply indicate optional parts of the command line.

Either filter style (the < and > are file redirection operators):
tth [-a -c -d ... ] <file.tex [>file.html] [2>err]

Or, specifying the input file as an argument (output is then implied):
tth [-a -c -d ... ] file[.tex] [2>err]

Switches:
-a automatic picture environment conversion using latex2gif (default omit).
-c prefix header "Content-type: text/HTML" (for direct web serving).
-d disable delimited definitions.
-e? epsfbox handling: -e1 convert figure to gif using user-supplied ps2gif.
-e2 convert and include inline. -e0 (default) no conversion, just ref.
-f? sets the depth of grouping to which fractions are constructed built-up
f5 (default) allows five levels built-up, f0 none, f9 lots.
-g don't guess an HTML equivalent for font definitions, just remove.
-h print help. -? print usage.
-i use italic as default math font.
-Lfile  tells tth the base file (no extension) for LaTeX auxiliary input,
enables LaTeX commands (e.g. \frac) without a \documentclass line.
-ppath specify additional directories (path) to search for input files.
-r output raw HTML (no preamble or postlude) for inclusion in other HTML.
-r2 omit just the time stamp. -r1 is equivalent to -r.
-t display built-up items in textstyle equations (default in-line).
-w? html writing style: 0 no title construction. 1 insert head/body.
-xmakeindx  specify a non-standard makeindex command line.
-v give verbose commentary.


With no arguments other than switches starting with a -'', the program is a filter, i.e. it reads from stdin and writes to stdout. In addition, diagnostic messages concerning its detection of unknown or untranslated constructs are sent to stderr. If these standard channels are not redirected using < and >, then the input is read from the command line, and both output and error messages are printed on the screen.

If a non-switch argument is present, it is assumed to be the name of the input file. The file must have extension .tex'' but the extension may be omitted. The output file is then constructed from the argument by removing the extension .tex'' if specified, and adding .html''.

TTH is extremely fast in default mode on any reasonable hardware. Conversion of even large TEX files should be a matter of a second or two. This makes it possible to use TTH in a CGI script to output HTML directly from TEX source if desired; (stderr may then need to be redirected.)

To discuss how to get the best from TTH, you can subscribe to a mailing list by sending an email containing the message subscribe tth_mailing_list to majordomo@hutchinson.belmont.ma.us. Then you can send messages to tth_mailing_list@hutchinson.belmont.ma.us.

## 4  Messages

Messages about TTH's state and its assessment of the TEX it is translating are output always to the stderr stream, which normally displays on the console, but under Un*x type systems can be redirected to a file if necessary. Normally these messages are one of three types:

#### Error Messages

These start **** Error: and indicate some improper condition or error either in TTH or in the TEX of the file being translated. Some errors are fatal and cause TTH to stop. On others it will continue, but the TEX file probably should be corrected in order to get correct output.

#### Warnings

These start **** but without reporting Error. They are messages by which TTH indicates aspects of the translation process that may not be fully satisfactory, usually because of known limitations, but which quite likely will not prevent the translated file from displaying correctly, and so do not necessarily require intervention. Examples include the use of dimensions, glue, or similar TEX commands that have no HTML equivalent.

#### Informational and external

Lines with no **** are either informational, meaning the state of the translation is not considered abnormal, or else they may come from external programs (e.g. makeindex), over which TTH has no control.

The switch -v causes more verbose messages to be output, which may be helpful for understanding why errors are reported. A higher level of verbosity -V can be invoked, but is intended primarily for internal debugging of TTH and will rarely be comprehensible!

The presumption that lies behind TTH message design is that the file being translated has been debugged using TEX or LATEX to remove syntax errors. TTH is not good at understanding or reporting TEX syntax errors and does not keep an exact count of line numbers (especially when \input is used). Therefore error reporting by TTH does not reach even the low standard of clarity set by TEX and LATEX error messages. Although TEX files can be debugged using TTH alone, since it is very fast, the process is not recommended for inexpert TEX users. Moreover, since TTH understands both TEX and LATEX simultaneously, it can parse some files that TEX or LATEX  separately cannot.

## 5  Mathematics

### 5.1  Equations

Equations are translated internally into HTML3.2 as much as it allows. TTH uses HTML3.2 tables for layout of built-up fractions in display equations. It also uses the HTML tag < font face=symbol'' > , part of the HTML4.0 specification, to render Greek and large delimiters etc. Untranslatable TEX math tokens are inserted verbatim.

The internal approach to equation translation is a major area where TTH departs from the philosophy of LATEX2html and its derivatives. TTH  does not use any images to try to represent hard-to-translate constructs like equations. Instead it uses the native ability of HTML to the fullest in providing a semantically correct rendering of the equation. The aesthetic qualities obtained are in practice no worse on average than LATEX2html's inlined images, which are generally slightly misaligned and of uncertain scaling relative to the text. Some limitations in the HTML code are inevitable, of course, but one ends up with a compact representation that can be rendered directly by the browser without the visitor having to download any additional helper code (e.g. Java equation renderer).

The option [-i]   to TTmakes italic the default font within equations, and thus the style more TEX-like. The italic font appearance in browsers is not as satisfactory as TEX's math italic, so for many documents roman looks better.

Spacing   in equations is handled slightly differently by TTH than by TEX. The reason is that most browsers use fonts that will crowd the characters horizontally too close for comfort in many cases (for example: M||/2). Also, built-up HTML equations are more spread out vertically than in TEX. Therefore TTH equations look better if spaces are added between some characters. So TT does not remove spaces in the original TEX file between characters in equations. The author is thus able to control this detail of layout in the HTML without messing up their TEX file - since TEX will ignore any spaces inserted. Legacy TEX code that contains a lot of spurious whitespace (ignored by TEX) may, as a result, occasionally become too spread-out when translated.

### 5.2  In-line Equation Limitations

Some TEX capabilities are extremely difficult or impossible to translate into HTML, because of browser limitations, and are best avoided if possible. Arrays or matrices in in-line equations cannot be properly supported because tables cannot be placed in-line in HTML. TTH output often will be strangely disjointed. Likewise built-up fractions, most over- and under-accents, and indeed anything that requires specific placement on the page other than simple subscript or superscript and underline, cannot be rendered in-line in HTML, although TTH will render them well in displaystyle. These latter constructs are nevertheless commonly used in in-line TEX. TTH adopts the default policy of indicating in an unambiguous and relatively intuitive way what construct is being used (as opposed to simply omitting it). For example $\hat{a}$ is rendered [^a]. The result is rarely elegant. Therefore in authoring TEX that is known to be destined for HTML translation, one should bear in mind these limitations, and use an appropriate style.

As an option, TTH provides switch -t to convert inline equations that use built-up constructs into a sort of half display, half in-line equation. Each time a new in-line equation is encountered [$...$ or $$...$$] that needs to be built up, an HTML table that starts a new line is begun, and the text then flows on afterwards. For example
 12 + n

This option gives a slightly disjointed layout for simple equations but is a big improvement for some situations, e.g. in-line matrices.

## 6  Features dependent on external programs.

### 6.1  Independence of [La]TEX installation and the -L switch.

A major difference between TTH and LaTeX2HTML is that TTH does not call the LATEX or tex programs at all, and is not specifically dependent upon these, or indeed any other (e.g. PERL), programs being installed on the translating system. Its portability is therefore virtually universal.

Forward references in LATEX are handled by multiple passes that write auxiliary files. TTH does only a single pass through the source. If you want TTH to use LATEX constructs (e.g. tableofcontents, bibliographic commands, etc.) that depend on auxiliary files, then you do need to run LATEX on the code so that these files are generated.

When run specifying a filename on the command line as a non-switch argument, TTH constructs the name of the expected auxiliary LATEX files in the usual way and looks for them in the same directory as the file. If you are using TTH as a filter, you must tell TTH, using the switch -Lfilename, the base file name of these auxiliary files (which is the name of the original file omitting the extension). If TTH cannot find the relevant auxiliary file because you didn't run LATEX and generate the files or didn't include the switch, then it will omit the construct and warn you. Forward references via ref will not work if the .aux file is unavailable, but backward references will. The -L switch with no filename may be used to tell TTH that the document being translated is to be interpreted as a LATEX file even though it lacks the usual LATEXheader commands. This may be useful for translating single equations that (unwisely) use the \frac command.

### 6.2  BibTEX bibliographies

TTH supports bibliographies that are created by hand using \begin{thebibliography} etc. Such bibliographies do not require anything beyond the .aux file. TTalso supports bibliographies created using BibTEX from a biblography database. The filename.bbl file is input at the correct place in the document. However, this filename.bbl is not created automatically either by LATEX or TTH. In addition to running LATEX on the source file to create the auxiliary file, you must also execute bibtex filename in the same directory, to create the filename.bbl file, and then run LATEX again to get the references right. (This is, of course, no more than the standard procedure for using BibTEX with LATEX but it must be done if you want TTH to get your bibliography right). If you don't create the .bbl file, or if you create it somewhere else that TTH does not search, then naturally TTH won't find it.

There are many different styles for bibliographies and a large number of different LATEX extension packages has grown up to implement them, which TTH does not support. More recently, a significant rationalization of the situation has been achieved by the package natbib. TTH has rudimentary support built in for its commands \citep and citet in the default author-date form without a second optional argument. A style file for natbib is distributed with TTHgold which makes it possible to accommodate most of its more useful styles and commands and easily switch from author-date citation to numeric citation.

### 6.3  Indexing

Indexing an HTML document is different from indexing a printed document, because a printed index refers to page numbers, which have no meaning in HTML because there are no page breaks. TTH indexes LATEX documents by section number rather than by page; assuming, of course, that they have been prepared with index entries in the standard LATEX fashion.

When processing a LATEX file that contains the \makeindex command in its preamble, TTH will construct an appropriately cross-hyperlinked index that will be input when the command \printindex is encountered, which must be after all the index references \index{ ... } in the document. TTH does this independently of LATEX, but not of the subsidiary program makeindex that is normally used with LATEX to produce the final index file.ind''. TTH creates its index entries in a file with extension .tid (Tth InDex). Because of makeindex program limitations, TTH currently removes all the page-number formatting that is present in the index entry (but not the reference formatting). It also uses the section reference style 1-2'', separated by a dash, because this is the standard form that makeindex expects and it is cumbersome to change it. The actual reference is less important to the reader than the fact that TTH inserts a link to the actual place in the document indexed. When the \printindex command is encountered, TTH closes this file and runs makeindex on it, which creates by default a file with extension .ind, and then TTH reads the .ind file in as its index. Because the .ind file that TTH produces may well be incompatible with running LATEX itself on the file, TTH deletes the .ind file that it creates (and hence one is left without such a file at the end). If, instead of creating an index file during TTH processing, one wants to use with TTH an index file already created, all that is needed is to remove the \makeindex command from the top of the LATEX source. Any existing .ind file will still be input by \printindex but no indexing files will be written or deleted.

If you run TTH on a file that contains both a \makeindex command and a \printindex it will overwrite your file.ind. In the unusual situation where your index, file.ind, was created laboriously by hand and cannot be recreated, you should be very careful to remove the \makeindex command from the .tex file. For safety, of course, also save a copy of your file.ind somewhere else.

The \makeindex command, if present, will also cause TTH to add a linked entry called Index'' to the end of any table of contents. This entry is a highly desirable feature for an HTML file, but if there is no \printindex command at the end of the document, the index will not exist, so the reference will be non-existent.

On some operating systems with file name length restrictions, the makeindex program is called makeindx. Therefore a TTH switch is provided: -xcommandline, which substitutes commandline for the default call makeindex. Therefore, -xmakeindx will switch to the correct program name on one of these limited operating systems. This switch also allows additional parameters or switches to be passed to makeindex via e.g.  -x"makeindex -s style.sty". If you don't have the makeindex program, you can't create indexes with TTH or LATEX, except by hand.

All of the index file processing naturally requires that TTH have write permission for the directory in which the original LATEX file (specified by the -L switch) resides.

### 6.4  Graphics Inclusion: epsfbox/includegraphics

The standard way in plain TEX to include a graphic is using the epsf macros. The work is done by \epsfbox{file.[e]ps} which TTH can parse. By default TTH produces a simple link to such a postscript file, or indeed any format file.

Optionally TTH can use a more appropriate graphics format, possibly using a user-supplied (script or) program called ps2png or ps2gif to convert the postscript file to a png4 or gif file, file.png'' or file.gif''. [file'' is the name of the original postscript file without the extension and png or gif are interchangeable as far as matters for this description]. When the switch -e1 or -e2 is specified, if file.png'', file.gif'' or file.jpg'' already exists in the same directory as implied by the reference to file.ps'' then no conversion is done and the file found is used instead. That graphics file is then automatically either linked (-e1) or inlined (-e2) in the document. If no such file is found, TTH tries to find a postscript file with extension that starts either .ps or .eps and convert it, first using ps2png then, if unsuccessful, ps2gif. Linux (un*x) ps2png and ps2gif scripts using Ghostscript and the netpbm utilities for this purpose are included with the distribution. A comparable batch program can be constructed to work under other operating systems 5 or else the conversion can be done by hand. Naturally you need these utility programs or their equivalent on your system to do the conversion. The calling command-line for whatever ps2png (or gif) is supplied must be of the form:

ps2png inputfile.ext outputfile.ext

The program must have permission to write the outputfile (file.png) in the directory in which the file.ps resides.

By popular request, a third graphics option -e3 for generating icons is now available. If no previously translated graphics file, e.g. file.png'' exists, TTH passes to ps2gif (or png) a third argument consisting of the name, file_icon.gif'', of an icon file. ps2gif is expected to create it from the same postscript file. In other words the call becomes

ps2gif file.eps file.gif file_icon.gif

This third argument is then the file that is inlined, while the larger gif file named file.gif'' is linked such that clicking on the icon displays the full-size gif file. The icon will not be created if file.gif'' already exists, because ps2gif will not then be called.

The LATEX2e command \includegraphics{...} and the older \[e]psfig{file=...} are treated the same as \epsfbox. Their optional arguments are ignored.

If the extension is omitted for the graphics file specification, then .ps or .eps is tried. If the extension of the file specified is non-null and not .ps or .eps, no conversion is done but the file is referenced or in-lined as an image. In effect, then, TTH supports postscript, encapsulated postscript, gif, and jpeg, plus any future formats that become supported by common browsers. However, LATEX does not support these other formats, so it will give an error message if it can't find a postscript file, unless you specify the bounding box, thus preventing LATEX interrogating the file.

### 6.5  Picture Environments

The picture environment cannot be translated to HTML. Pictures using the built-in LATEX commands must be converted to a graphics file such as a gif, and then included using \includegraphics, see 6.4. The switch -a, causes TTH to attempt automatic picture conversion using a user-supplied routine latex2gif. When this switch is used, TTH outputs the picture to a file picn.tex, where n is the number of the picture (if there does not already exist a file picn.gif). It then calls the command latex2gif picn which must be a command (e.g. a script using LATEX, dvips, etc.) on the system, which converts the file picn.tex to a file picn.gif. An example linux script is included in the distribution but this conversion script is dependent on the system and so is entirely the user's responsibility. For viewing the results, the files picn.gif must be accessible to the browser in the same directory as the HTML files, then they will be included in-line. It is impossible for a picture environment to be converted in this automatic fashion if it contains macros defined somewhere else in the original LATEX file, because the macros will then be undefined in the picture file that is extracted, and LATEX will be stumped. In that case, manual intervention is necessary.

## 7  Tabular Environment or Halign for Tables

The tabular environment is the recommended way to construct tables in LATEX. In plain TEX, although \settabs etc. is supported, the \halign{ ... } command is recommended. (The LATEX tabbing environment is not supported by TTH because it is antithetical to the spirit of HTML document description, and because it is an extremely complicated construct. If you are lucky, TTH will not mess up your tabbing environment too much, but it makes no attempt to interpret it properly.) Considerable effort has been expended to translate the tabular environment, including interpreting the alignment argument of the environment, into as near an equivalent in HTML as reasonably achievable6. However, the limitations of HTML tables impose the following limitations on the translation.

### 7.1  Tabular

• HTML tables have either all cells bordered with rules or none. TTH therefore decides whether to use a bordered table by examining the first character of the alignment argument. If is it |, then the table is bordered, otherwise not.
• HTML tables are not capable of simultaneously aligning part of a cell's contents to the right and part to the left, which is automatically done by LATEX on some occasions when @-strings are used. For example if the alignment argument is |l@{~units}|r|, LATEX will align units'' to the right of the first cell. TTH can't. In some unbordered cases TTH will try for the same effect by putting the closing @-string in the following cell. This won't always give a good result.
• @-strings and *{num} code repetition are not permitted in the alignment argument to \multicolumn, but they are in the main tabular alignment argument.

### 7.2  Halign

• TTH decides whether to use a bordered table in Plain TEX by examining the entire halign template (i.e. the material up to the first \cr of the halign). If it contains the command \vrule TTH makes the table bordered, otherwise not.
• TTH decides on the alignment of the cell contents by looking for \hfill or \hss commands in the cell template. The default is to left-align the cell. If one of these spacing commands is present in the template prior to the # for this cell, then the cell will be right-aligned unless such a command also appears after the #, in which case the cell is centered. Again HTML is not capable of applying different alignments to different parts of a cell. So results may sometimes be different from TEX. However, if most of this paragraph sounds totally obscure to you, don't worry; TTH will probably do the right thing.
• The \multispan command is supported, giving a centered multicolumn cell, and \omit is treated as \multispan1. However, \span is currently not supported.

### 7.3  Longtables

• The longtable environment is supported, but it is always centered. It is converted into a standard tabular inside a table environment because there is no need to accommodate page breaks (the main point of longtable) in HTML.
• The caption (including caption*) command is translated correctly but set as part of the HTML table; so, if the caption is longer than the longest row of the table, it will cause the whole table width to expand, possibly up to 100% of the line-width.
• The commands endhead, endfirsthead, endfoot, endlastfoot, are ignored, but their immediately preceding commands are therefore inserted into the table. That is probably not desirable for the foot commands. Longtable footers are not translated into footers.
• The \kill command is ignored. Its text is spuriously inserted.

## 8  Boxes, Dimensions, and fills

Boxes, dimensions, and fills are rarely appropriate for web documents because they imply an attempt to control the fine details of layout. Browsers make their own choices about layout of a document in HTML. For example they make the lines fit whatever size of window happens to be present. This dynamic formatting makes mincemeat of most detailed TEX layout. Therefore the best advice is to avoid these constructions as far as possible.

There are nevertheless many cases when a TEX document containing boxes, dimensions, and fills needs to be translated. Earlier versions of TTH made a point of trying to intercept the dimensions and drop them, so as not to clutter the HTML with rubbish. From version 2.5 onwards, limited translation of these constructs is supported. They are translated, where appropriate and possible, into HTML tables with widths and vertical skips estimated to give a reasonable result on a browser. It must be stressed that accurate translation is inherently impossible because browsers deal in pixel sizes and default font sizes that vary and are out of the control of the publisher.

The types of box usage that translate quite well are when things like

\hbox to \hsize{The left \hfil the Right}
\vbox{\hsize=2in Matter to be set in horizontal mode to a
limited hsize}
\makebox[0.6\hsize][r]{Stuff to the right of the makebox.}
\framebox{check}


are on a line by themselves. You get:

 The left the Right

 Matter to be set in horizontal mode to a limited hsize

 Stuff to the right of the makebox.

 check

Usages that translate poorly tend to be boxes within a line of text. That is because current HTML table implementations have to start a new line unless they happen to be adjacent to a table already. Thus an hbox in a line will give a line break that you might not have wanted. This behaviour is really a bug in the browsers, but we are currently stuck with it. The behaviour of HTML tables is buggy [see 12.6] when their alignment is specified, which means that strange results are likely if more than one box on a line is being set. Boxes in equations are troublesome. The only type that is reasonably supported is \mbox which is often used in LATEX for introducing text inside equations.

Usages that are currently not supported at all include negative skips, \newdimen new dimensions.

The only important dimension parameter that is currently supported is \hsize. This can be reset using the plain TEX format e.g. \hsize = 3in but only within a group, because it makes no sense for the HTML file to try to specify the width of the line at the outermost level, which is the browser's business.

TTH trys valiantly to mimic the sort of text alignment that is obtained using glue such as \hfil and \hss, provided it is inside a box. However, the alignment algorithm of HTML tables makes it impossible to obtain fills with exactly equal sizes. So don't be surprised if some results looks disagreeable. Moreover, TTH will completely ignore the glue outside an hbox, and it doesn't know the difference between \hfil and \hfill, etc.

## 9  TEX command definitions and other extensions

### 9.1  Delimited-parameter macros and Conditionals

Delimited parameter definitions are fully supported. However, macros in some style files are written in such a way that the recognition of the delimited parameter depends on other TEX behaviour (e.g. dimensions) that are not supported by TTH. In such cases it is all too possible for the delimited parameter not to be matched, resulting in a runaway argument situation. Thus, delimited parameter macros are especially dangerous when using TTH, or indeed any process other than TEX itself. (And they are never exactly safe TEX''). The recognition of these definitions can be disabled using the -d switch, in which case the definitions are simply discarded.

Conditionals such as \if, \ifnum and so on are supported, as listed above (1.1.2). In TTH they have one syntax limitation. Further if' commands are not permitted in, or as part of a command expanded in, the tokens, characters, or numbers being tested. Thus, an example of truly perverse usage such as
\ifnum 1=\if ab 1\else 2\fi True \else False \fi
will likely break. Nested if' constructs are permitted in the conditional text, however, so
\ifnum 1=1 True\if ab -true\else -false\fi \else False \fi
is fine. Because TTH does not internally resemble TEX, whereas the result of conditionals such as \if and \ifx may depend on internal representations, there cannot be 100% compatibility of such tests at the lowest level. Still, tests on externally defined commands ought generally to give correct results. When authoring documents in TEX one is generally well advised to avoid conditionals.

Although TTH supports a remarkably complete subset of LATEX, it does not support all of the complicated primitive details of TEX, partly because that would be unnecessary. For example, practically any TEX that redefines category codes (other than @ which TTH treats universally as a letter) will break because TTH knows nothing about the concept of category codes. (If you don't know much either, about this unfortunate aspect of TEX, join the vast majority of TEX users!) A related example is that TTH expects only letters or @ in user-defined command names, not punctuation characters etc.

### 9.2  Macro- and Style-file inclusion

Macro definitions are fully supported by TTH. However, special macro packages designed for a specific layout of journal or conference, for example, often use new dimensions or other unsupported constructs such as catcode changes. It may then be inadvisable to use the macro package. That is the reason why TTH does not normally have directory paths defined the same as TEX. If a macro package is then on the TEXINPUTS path it will be found by TEX but not by TTH. Thus, the macro definitions are included when TEX''ing the file, but not when TTH''ing it.

TTwill find an input file if

1. the full path is specified relative to the directory from which TTH is run, e.g.
\input /home/myhome/mytexdir/mymacro.tex
2. the -p switch specifies a path on which the file is found, or
3. the TTHINPUTS environment variable is defined to be a path on which the file is found.
Paths are searched in this order until an appropriate file is found or all directory options are exhausted

This policy provides a mechanism for making available the alternative package for TTH, without alteration of the original TEXfiles, by placing the (simplified) version of the macro package on the path TTH searches. An example using the -p switch might be

tth >file.html <file.tex -p/usr/local/tthinputs:~/mytthinputs



Since it is impossible to anticipate all style file incompatibilities, it must be the responsibility of the user (or the journal) to decide how to translate the concepts implemented in the original complicated macro package into simpler, TTH-compatible, TEXmacros.

### 9.3  Layout to include arguments of unknown commands

Unrecognized or undefined commands of the form \dothis{one}{two}{three}, are treated by discarding all the following adjacent brace groups. A space between the close and open braces will terminate the discarded arguments and cause the following brace group(s) to be scanned as if just the text. This makes it possible to use formatting to make TEX code come out right in both TEX and HTML. For example if TTH encounters a command written \boxthis{width} {boxed material}'' which might be designed in TEX to provide a width to a defined command, written with a space after the first argument, it will ignore the width and scan the boxed material into the text.

### 9.4  Restrictions on redefinition of internal commands

In TTH (unlike TEX) most internal commands can not normally be redefined; any redefinition will simply be ignored (except inside edef and a few other places). This prevents TTH from safely allowing use of major packages that redefine standard TEX commands. For example amsTEX redefines footnote to have just one argument, which will cause problems. This particular example is potentially a problem with LATEX too, which also redefines footnote. TTH handles this by keeping track of whether the file is LATEX or TEX; therefore you should not mix the two dialects in a single file even though there is no need to tell TTH explicitly which type the file is. (Besides, a mixed file will play havoc with TEX itself.)

#### 9.4.1  Footnotes

Footnotes are placed together at the end of the document, or, in the case of TTHgold splitting files, in a separate file called footnote.html. The title of this end section is determined by the macro \tthfootnotes. By default this is Footnotes'', but can be redefined by the user at will, e.g. by \def\tthfootnotes{Tailnotes}.

## 10  Color

TTH supports the coloring of text using the color package macros for LATEX, supported by dvips (but not xdvi). TTH also supports the Plain TEX colordvi macros contained in the package colordvi.tex that do the same thing.

### 10.1  LATEX Color

The LATEX syntax is recommended because the 68 standard named colors7 are directly supported internally by TTH using the named model. Any numerical CMYK, RGB and Gray color can also be prescribed. For example the following commands are enclosed in themselves: \textcolor[named]{BrickRed}{...}, \textcolor[rgb]{0.,.5,0.}{...}, \textcolor[cmyk]{0.,.5,0.,0.3}{...}. You can define custom colors in the usual way using, for example

{\definecolor{Puce}{rgb}{1.,.5,.8}
\color{Puce} This is my own Puce.}


Which gives  This is my own Puce.''

The command \pagecolor is supported but discouraged. It is highly likely to give rise to an HTML file that will fail validation because it inserts an HTML tag <body bgcolor=...> which will not be in its correct position (immediately following the title). The only way to be certain to produce an HTML file that passes validation is to put the title and body commands in by hand, using e.g. \special{html:<title>...</title><body ...>} Netscape seems not to mind a body tag out of order, but only the first one is able to set the page background color.

The commands \colorbox and \fcolorbox are supported via CSS style sheet commands. They will only work to set the background color of included text if the browser is set to use style sheets. This sentence'' is the result of the command \colorbox{green}{This sentence''}. If it is colored, then your browser supports style sheets to this extent. If not, check your preferences settings.

### 10.2  Plain Color

The Plain TEX syntax using commands such as \Red{red text} requires the file colordvi.tex to be input prior to their use. But because TTH does not search the standard TEX paths, that file will not usually be found unless the full path is explicitly specified. If the file is not found, only the 8 standard colors

\Red, \Green, \Blue, \Cyan, \Magenta, \Yellow, \Black, and \White


are recognized internally by TTH. You can use the user-defined CMYK numeric style
\Color{0. .5 .5 0.}{pale red}


without the colordvi file. It gives the result pale red'' but the notation becomes cumbersome unless you define your color e.g. like
\def\redcolor{0. .5 .5 0.}
\Color{\redcolor}{The stuff that is red.}



Another difficulty with the colordvi command \textColor (which is the color switch - LATEX syntax reversed that usage and changed to comma-delimited arguments just to confuse us) is that it is a global setting. It then becomes almost impossible to maintain proper nesting of the closure of the font commands used for colors in HTML. As a result, use of \textColor often gives HTML files that won't pass HTML validation.

### 10.3  Limitations

Color commands do not propagate into different cells of HTML tables because of what may be regarded as a browser bug [12.6]. For that reason, tables and equations will not color correctly if the color commands enclose more than one cell (for tables) or equation element. Remember also that some computers may be limited in their color display capability, so the subtleties of colors will be lost in some circumstances.

## 11  HTML and output

### 11.1  Formal HTML validation

TTH takes as its standard HTML that can be rendered by Netscape and IE browsers versions 3 and higher (with the caveats above). Documents without mathematical symbols, translated by TTH, conform to the HTML3.2 standard. Since the font tag needed for symbols is not part of the HTML3.2 standard, any such symbols compromise that formal standard. Therefore the formal standard that TTH-translated documents follow is strictly HTML4.0 Transitional. However, TTH does not formally validate its documents, and can be made to violate the standard by some TEX usage.

One reason for violation arises because HTML4.0 requires a <title>...</title> for every document. A title is constructed from LATEX files that contain the \title{...} command, in which case HTML conformance is ensured by putting the \title command before any text (i.e. in the preamble, where it belongs). If the \title command is not desired in the TEX file, for example because it is a plain TEX document, a title can be provided by the author for the HTML document by putting a line like this at the top of the TEX file.

%%tth:\begin{html}<title>Put the title here</title>\end{html}


This line will be ignored by TEX. Actually, any raw HTML output at the start of the file is assumed by TTH to indicate that the author has explicitly output a title. If no title indication of any of the above types is present, TTH attempts to construct a title from the first few plain words in the document, in much the way that the first line can become the title of a hymn.

If commands like \item, that output material to the HTML file occur before the title has been constructed, the HTML title command will be out of order and the formal standard will be violated.

In the case where the title construction fails, or if some other TEX usage causes a violation of the formal standard, browsers will still render the output correctly if this manual is followed.

### 11.2  HTML Styles

There are good reasons why the <head> and <body> tags are by default omitted by TTH. See the FAQ [B] for a brief discussion. However, the evolution of HTML standards (not browsers) is towards imposing more restrictions on the freedom to omit tags. For example XHTML requires that containers have both opening and closing tags. Therefore TTH has a switch -w? (where the question mark denotes an optional integer) that controls its writing style. At present, in addition to the default style that attempts to construct a title but does not enter head and body tags, -w or equivalently -w0 prevents TTH from attempting to construct a title or anything else in the way of head/body divisions. This style is best used for documents where the author has explicitly entered the required HTML tags. The switch -w1 invokes pedantic HTML style which enters head and body tags under the assumption that the title (possibly constructed automatically) is the last thing in the head section. A style -w2 produces XHTML documents but requires cascading style sheet (CSS) support in the browser otherwise the rendering will not be as satisfactory as the default. Also, the restrictiveness of XML syntax requires that each paragraph be a separate group. As a result, TEX commands like \it, whose scope extends until the current group is closed, only apply in HTML documents until the end of the current paragraph, not TEX group. This is a significant incompatibility, but in any case the switch -w2 is not recommended for production documents until the CSS bugs in popular browsers are ameliorated. However, it would be helpful to hear of confirmed violation of the XHTML standard on test documents using the -w2 style switch.

## 12  Browser Problems

TTH translates TEX into standard HTML and takes account as far as possible of the idiosyncrasies of the major browsers. Nevertheless, there are several problems that are associated with the browsers. Authors and publishers should recognize that these are not TTH bugs.

### 12.1  MacIntosh browser font problems

The characters with codes higher than 127 in the Mac fonts are in a different order from the standard ISO-8859-1 (sometimes called ISO Latin-1). If Netscape or IE on Macs have their document encoding set to the standard, then in versions 3 onwards they are programmed to access the glyph where they think the corresponding accented Latin character will be in the Mac font. This is fine if one really wants an accented Latin character. However, for mathematics, using the symbol font (which is ordered the SAME on the Mac as on other platforms) the result is that one gets the wrong symbol glyph. This is a particular problem with large delimiters. The fix is that the Mac browser must be set to use the Options/Document-encoding MacRoman". This tells the browser not to do the permutation to access the accented Latin characters in the Mac places; hence, for eight-bit characters, it accesses the symbol font correctly. This would break the Latin accented characters except for the fact that (most current versions of) the browsers still access characters in the Mac order if they are specified numerically using the HTML syntax &#???;". So TTH documents will in most cases display both accented characters and symbols correctly on Macs if the document-encoding is set to MacRoman.

In addition, NS4.0 has under Edit Preferences Fonts a choice between use document fonts'' and use my fonts overriding document''. You need to set use document fonts''. This necessity is obvious if you think about it. You can make any document into garbage by specifying your own font (e.g. Greek or Cyrilic) that happens not to be what the document is written in. The same is true for the symbols of mathematics. The reader must permit the document to specify the font. Browsers should always set use document fonts'' as the default.

In summary, you might want to tell people viewing your documents to set their browsers to View Encoding MacRoman, and Edit Preferences Fonts Use-document-fonts (NS 4.0).

### 12.2  Netscape Composer

Netscape Composer (in Netscape Communicator 4.0 on) is too clever for its own good. If you run an HTML document produced by TTH through Netscape Composer, all sorts of internal translations are performed that are detrimental to its eventual display. For example, if you subsequently save the document with the usual encoding set (Western), the eightbit codes that work with Macs are replaced with HTML4.0 entities such as [&]ograve; or [&]pound;. This effectively breaks the document for viewing on Macs because it undoes everything just explained. Even if you use User-Defined encoding, which prevents this particular substitution, Composer will rearrange the document in various ways that it thinks are better, but that make the display of the document worse. The moral is, don't run TTH documents through Netscape Composer. You therefore cannot use the publish'' facility of Composer. Transfering the document to the server with plain old ftp will keep it away from Composer's clutches.

[Unconfirmed reports indicate that P*gemill has problems of the same type.]

### 12.3  X font problems

Symbol fonts are not normally enabled for Netscape running under X, because of the way Netscape groups its fonts. A fix for this is to install some aliases in the fonts directories or else to add a line to your .Xdefaults file. See http://hutchinson.belmont.ma.us/tth/Xfonts.html. You might want to put these notes on your site for people viewing your documents.

A font rendering problem exists for small size single-symbol overbar in the Xfree86 server. The overbar symbol may or may not appear, depending on the direction in which its window uncovered. (Yes, this is a really bizarre bug but can be demonstrated with the xfd program.) It is strictly not a Netscape bug but an X-server, or perhaps font, bug. This symbol is used by TTH only as a fall-back for \bar in situations like in-line equations where it can't render the construct using tables.

### 12.4  Internet Expl*der

IE 4.0 renders nested sub- and superscripts wrong under Wind*ws 95/8 so that for example the HTML x<sup>n<sub>i</sub></sup> is rendered as if it were x<sup>n</sup><sub>i</sub>. Here is the first form: xni to test your browser. Tests on Win 3.1 with IE 3.01 show no such problem. Obviously this is a fairly serious bug for mathematics that ought to be fixed by the browser programmers. [Let MS*ft know if you observe it, so that plenty of people are complaining and they might fix it.]

### 12.5  Printing

In Netscape 3.0 and 4.x under X, for example, the printing fonts are hard coded into the browser and the font-changing commands are ignored when printing. For that reason, visitors viewing TTH documents will often not be able to print readable versions of documents with lots of mathematics. This problem could, and should, be fixed in the browsers. However, if you want your readers to be able to print a high-quality paper copy of the file, then you probably want to make available to them either the TEX source or a common page-description format such as Postscript or PDF. Since HTML documents download and display so much faster and better than these other formats on the screen, TTH's translation provides the natural medium for people to browse, but not necessarily the best medium for paper production.

### 12.6  Other Browser Bugs

Under Wind*ws, both Netscape (3.0) and Internet Expl*rer (3.02) incorrectly size or space vertically the symbol glyphs so that small gaps appear between the parts of large symbols and delimiters. This occurs only at certain font sizes (different between the two browsers!) but causes a slightly annoying degradation of the appearance.

Both Netscape and IE fail (although somewhat differently) to carry font changing commands from cell to cell of HTML3.2 tables. In rendering equations (using tables) TTH circumvents this bug at the cost of significant extra effort and slightly verbose HTML. However, for tables generated by \halign or \begin{tabular} TTH takes no special steps to avoid this bug. Therefore you cannot, for example, increase the font size of an entire table by enclosing it in {\large ... } and indeed the table will revert to the default size even if it is inside a different sized section of text. Moreover, a change of font face in a cell, for example by \it will not carry over to the next cell. A document containing this problem will not pass some HTML validations. It is prevented if every cell of a TEX table is enclosed in braces and the required style applied separately to every cell - a serious annoyance.

IE can become confused about its vertical alignment in tables, with the result that symbols float above or below the horizontal line in built-up equations. This sometimes fixes itself if you simply refresh the page!

Tables are incapable of being properly embedded within a line of text. They generally force a new line. This is quite a significant handicap when translating in-line material that could use a table. It can be argued that this behaviour is required by the HTML standard. Specifically, the <p> element is defined as having in-line attributes which prevent it from containing any elements defined as being block type, of which <table> is one. However, here the standard seems to be very unhelpful.

Nested tables in Netscape 4.x are not properly cleared by the <br clear=all> attribute. It appears that the next line is shifted down only by the height of the last innermost table in the nest. If this happens not to be the tallest table, the subsequent text will overwrite that tallest table. This sometimes the cause of problems when putting more than one box on a line.

On Macintosh Netscape, the standard HTML entity &times; for a multiplication sign is not recognised. There seems to be no good reason for this omission. Complain to the browser manufacturer!

### 12.7  Cascading Style Sheets and Unicode

The facilities offered by style sheets make it possible in principle, but not currently in practice, to solve several of the outstanding layout problems that TEX translation encounters. Unfortunately, in practice, the latest versions of the popular graphical browsers offer only incredibly buggy and broken implementations of the parts of CSS that are needed for mathematics layout, and they are essentially unusable for this purpose. (Here Netscape is the worse offender.) The use of unicode is advocated by purists instead of using the symbol font. However, again, there is no practical way to use it reliably in the current browsers.

## 13  Code Critique

If you think you have found a bug, you can report it to the mailing list mentioned in section 3. You are most likely to get help if your report is accompanied by the brief section of TEX code that causes the problem. But please don't send LATEX2.09 files or files that do not conform to the latest (1994) LATEX users' guide. And please check this manual and especially the FAQ (B) first.

The code has been compiled and run on Linux, MSDOS, Wind*ws, Open VMS, and sundry other operating systems. See http://hutchinson.belmont.ma.us/tth/platform.html.

You may freely use TTH for non-commercial purposes. It may not be used for commercial purposes. If you distribute any copies, you must include this file and these conditions must apply to the recipient. TTHgold may be used for commercial purposes according to its license. No warranty of fitness for any purpose whatever is given, intended, or implied. You use this software entirely at your own risk. If you choose to use TTH, or TTHgold, by your actions you acknowledge that any direct or consequential damage whatever is your responsibility, not mine.

## 15  Acknowledgements

Many thanks for useful discussions and input to Robert Curtis, Ken Yap, Paul Gomme, Michael Sanders, Michael Patra, Bryan Anderson, Wolfram Gloger, Ray Mines, John Murdie, David Johnson, Jonathan Barron, Michael Hirsch, Jon Nimmo, Alan Flavell, Ron Kumon, Magne Rudshaug, Rick Mabry, Andrew Trevorrow, Guy Albertelli II, and for bug reports from others too numerous to mention.

## A  Appendix: Non-Standard TEX Macros

The following macro definitions, although not needed for TTH, will enable a TEX file that uses the non-standard TTH commands to be correctly parsed by Plain TEX.

\def\hyperlink#1#2{\special{html:<a href="\##1">}#2\special{html:</a>}}
% Incorrect link name in \TeX\ because # can't be passed properly to a special.
\def\hypertarget#1#2{\special{html:<a name="#1">}#2\special{html:</a>}}
\long\def\tthdump#1{#1} % Do nothing. The following are not done for TtH.
\tthdump{%
\def\title#1{\bgroup\leftskip 0 pt plus1fill \rightskip 0 pt plus1fill
\pretolerance=100000 \lefthyphenmin=20 \righthyphenmin=20
\noindent #1 \par\egroup}% Centers a possibly multi-line title.
\let\author=\title % Actually smaller font than title in \LaTeX.
\input epsf     % PD package defines \epsfbox for figure inclusion
% Macro for http reference inclusion, per hypertex.
\def\href#1#2{\special{html:<a href="#1">}#2\special{html:</a>}}
\def\urlend#1{#1\endgroup}
\def\url{\begingroup \tt
\catcode\_=13 % Don't know why this works.
\catcode\~=11 \catcode\#=11 \catcode\^=11
\catcode\$=11 \catcode\&=11 \catcode\%=11 \urlend}% \url for plain \TeX. }  ## B Appendix: Frequently Asked Questions Why won't TTH run under DOS? Something about DPMI. It will, but the distributed DOS executable needs DPMI memory extension support to run. Plain old DOS doesn't have that unless you specifically load it. All Wind*ws versions from 3.1 on support it at the DOS prompt. Why won't TTH run from Program Manager in Wind*ws? You need a command line. Call up the DOS prompt. TTH does not recognize tableofcontents, backward references, listoffigures, ... Yes it does, see section 6.1, and use the -L switch. TTH does not insert my picture environments. If picture environment pictures are to be included, conversion to a gif file is needed. See 6.5. TTH messes up my tabbing environment. Tabbing is not currently supported. It is alien to the HTML document mark-up approach. See section 7. How do I make TTH border my tabular table? TTH looks in the format string argument of the begin{tabular} environment and if it begins with a | (vertical bar) then the HTML table is bordered. TTH inserts the title and author even without the maketitle command True, TTH inserts them when you define them. This gives you a chance to fine-tune the presentation if you wish. Why doesn't \frac work in equations? It does, but only in LATEX documents because \frac is not a plain TEX command. The document you are presenting to TTH doubtless has no \documentclass command and other LATEX blurb at the top. If you insist on having LATEX commands available in such a document, you can use the -L switch. But note that other changes in interpretation (e.g. in footnotes) are implied by using this switch to tell TTH that this is a LATEX file. What is this strange result using \dot \hat \tilde \frac \vec ... in in-line equations? Neither over and under accents nor built-up constructs such as fractions can be rendered in-line (i.e. in a textstyle equation produced by$ ... \$) in HTML. Therefore, TTH outputs something that is not elegant but reasonably indicates the original intention. Additional brackets are inserted to ensure that fractions are unambiguous. TTwill render all these built-up constructs correctly in a display equation. See also 5.2 for an option.

Why does the large square root sign look so ugly?
There are some things that browser symbol fonts can't do well.

Why does a dagger sign come out strange?
Browsers don't generally have a dagger sign in their fonts. TTH uses a kludge.

How do I insert code that is used only by TTH, not TEX?
Use %%tth: followed by the material you wish to pass to TTH. TEX omits this line as a comment. Alternatively, insert \newif\iftth at the top of your document, then use a conditional: \iftth \TtH\ material \fi. TtH recognizes \iftth as a special if' that is always true, whereas to TEX it is simply a new if', which by default is false when defined.

How do I insert HTML tags into my file without TEX knowing?
Use %%tth: then on this line put \begin{html} tags \end{html}. Do not try to continue this html onto a second line with a second %%tth: before the \end{HTML} because the html environment will output the %%tth:, which it probably not what you want. Another way to pass codes directly to the output is the \special{html: ... } command. Do not use \begin{verbatim} to pass HTML tags. It will convert the greater than and less than signs to make them appear in the display and not be interpreted as tags.

How do I insert code that is used only by TEX, not TTH?
Insert \newif\iftth at the top of the file and then use the conditional constr uction:

\iftth\beginsection{The \TtH\ Header}\par\else\beginsection{The \TeX\ Header}\fi


The else' clause may also be used with a blank first clause, of course: \iftth\else ... \fi. Alternatively, insert the definition \def\tthdump#1{#1} at the top of the file and then use \tthdump{\TeX\ material} to pass stuff only to TEX. The command \tthdump is an internal command for TTH (which cannot be redefined) that simply discards its argument. Thus, for example, the following will output alternate versions from TEX and TTH.
\def\tthdump#1{#1}



How do I include the style file ...sty for the TEX paper I prepared for... journal?
If you are wise, you probably don't. TTH often can't handle complicated journal formats for [La]TEX without modification, because they frequently use newdimens, and category code modification or other unsupported constructs. Instead, look at your TEX file, or the TTH messages telling you which commands are unknown. Decide which of the journal's specific commands or environments you used or need. Write a little style file that defines them to do something simple and sensible, or translates them into standard LATEX commands. Or ask the journal to provide such a style file! If you are a journal publisher, distribute your simplified style file to your authors.

Why does TTH not recognize my ends of lines properly?
If you transfer a file from one operating system to another as a binary file, the line-end codes are likely to be messed up. They use different codes on Un*x, DOS, and Mac. Usually TEX is not bothered by this. TTH is somewhat more sensitive. Use ASCII transfer.

TTH does not recognize evironment ... even though it claims to.
Probably you left a spurious space, e.g. \begin {enumerate} between the \begin and the following brace. TTH occasionally won't accept that, even though LATEX does. It is bad style.

Why does TTH not recognize ... command from ... style package?
Let's be perfectly clear here. TTH does not currently recognize \usepackage and, with the exception of commands explicitly mentioned in this manual, does not support any of the zillions of extensions to LATEX that exist, even if they are part of the standard distribution''.

The file I published'' using Netscape Composer looks messed up when viewed on a Mac.
Don't use Composer on TTH documents. See section 12.2.

In bordered tables I want an empty cell to look empty. How do I make TTH do that?
HTML tables by default fill in'' an empty cell, so that it gives the visual impression of being absent. This is sometimes useful, so TTH does not prevent it. If you want it to look like an empty cell, put a non-break space in it by &~& in the TEX.

Why does TTH mess up my \fbox, minipage, etc?
The whole concept of a box'' is not really translatable into HTML. TTH tries to mimic the box using tables. But in some cases, especially in equations, it can't cope.

Why does TTH complain about my skip, space, ... command?
Dimensions are usually inappropriate for HTML. TTH tries do something sensible with dimension, space, and glue commands. Usually it is successful. If so, you need do nothing. In some rare cases, you might see some irrelevant left-over characters from the dimension command that have to be removed by hand.

How do I get caligraphic fonts, {\cal E}, AMS fonts, etc?
You can't because browsers don't have access to them. TTH can only support fonts that are available on the browsers that eventually visit the page. By default TTH tells the browser to render caligraphic as italic helvetica font. You may, if you wish, define \cal to be something different, such as %%tth:\def\cal{\it\color{red}}.

Why does TTH turn double-quotes into an accent instead of quotes?
In basic TEX the double quotes character " is not defined, and hence may do anything that the local installation feels like. Double quotes must be inserted by using two quote '' or back-quote  characters. In German TEX implementations, the double-quotes character is used to provide the umlaut over accent and for some other special needs. TTH supports these German uses in some appropriate contexts. English speakers should adopt proper TEX quote usage. There is essentially never a situation in LATEX where it is advisable to use a double quote to represent itself outside of a verbatim section (where it will naturally be treated literally). In Plain TEX you might need it. If so, \char" is an absolutely fool-proof way to insert it. Here it is:". You can also just enclose it in braces thus:{"}.

How do I include into a macro I am defining a # sign for an HTML reference?
When you do \special{html:<a href="#reference">} TTH just puts the html tag in the output verbatim. TEX does essentially the same for its dvi file and the dvi processor later may or may not complain about not understanding it; but generally it is ignored. However if you try to define a macro like \def\localhref{\special{html:<a href="#reference">}} then TEX will complain as follows:

! Illegal parameter number in definition of \localref.
r
l.3 \def\localref{\special{html:<a href="#r
eference">}}
?

This problem is caused by TEX's syntax analysis of the contents of the definition. One solution is to hide the definition from TEX using %%tth:. An alternative definition that avoids this problem must also be included for TEX's benefit, for example thus:
\def\tthdump#1{#1}
\tthdump{\edef\localref{[a hyperreference]}}
%%tth:\def\localhref{\special{html:<a href="#reference">}}


Alternatively, use \# in place of # in the hypertex reference. TTH specifically recognizes this as a literal and does appropriate translation. For example
\def\localhref#1#2{\special{html:<a href="\##1">}#2\special{html:</a>}}


will use its first parameter as a local anchor reference, preceded by #, and its second as the text of the anchor. The sequences \% and \\ are also treated as escaped literals, inserting their second character, inside a raw html section.

How do I construct a macro to take as a single argument a URL, which may contain special TEX characters like _ ~ @ & etc, that makes TTH construct a hyperreference but TEX just enter it in the text?
Use the built-in command \url{...}. This behaves in essentially the same way as the command defined in LATEX's url.sty. The reference will appear verbatim in the text (in teletype font).

TTH seems not to work on WinNT when converting included PostScript files, even though my ps2gif program works fine from the command line. What is the problem?
The problem is not TTH. It appears to be an operating system problem. The batch program ps2gif is breaking for some strange reason when called from TTH. See footnote 5.

Why doesn't TTH automatically generate <head> and <body> HTML tags?
First, the <head> and <body> tags are optional in the HTML specification. There is no need for TTH to generate them to statisfy the standard. Second, TEX and LATEX files do not have a corresponding structural division into separate head and body sections. It might seem as if LATEX does, with \begin{document} being the divider, but there are many cases where this mapping is incorrect. For example title may not be defined until after \begin{document}, corresponding to the HTML body section, whereas it must be in the head section. Finally, if TTH automatically entered <head> and <body> tags, then the thoughtful author would not be able to enter them where they ought to be by using, for example:
Therefore, the choice not to produce these tags automatically is a deliberate one based on a careful consideration of the advantages and disadvantages. An author can always adjust their TEX code to include them, if they wish to be pedantic about the division. See also the section on HTML style [11.2].

Why don't TEX commands get expanded in the HTML title?
In HTML, the stuff that goes in the <title>...</title> of a page is not permitted by the specification to contain HTML tags - things in angle brackets - and tags are not interpreted. If an equation or some other command that TTH translates into HTML formatting is in the title, then the title will break when expanded. Therefore TTH never expands commands in the title, but leaves them in the TEX form that they started as, since that is about as easy to read as any unformatted mathematics.

Can TTH be made to support BibTEX bibliographies?
It already does; see 6.2. If TTH is not finding the .bbl file even though you used the -L switch, then you probably forgot to generate it using LATEand BibTEX, or perhaps it is in the wrong place.

Does TTH support ...?
Probably yes if it is part of LATEX. But if you want a specific additional capability, and find that it is not supported, why not write a TeX macro to support it and translate it into suitable HTML using the functions described in this manual. Then you will have your support and if you send it to tth@hutchinson.belmont.ma.us it may be possible to include it into the standard TTH executable and you'll have helped all the other users of TTH.

## Index (showing section)

&times;
Mac browser bug, 12-6
LATEX extension packages, B-0
TEX-only code, B-0
TTH-only code, B-0
auxiliary files, 6-1
BibTEX, 6-2
<body>, B-0
bugs, 13-0
calligraphic, B-0
CGI script, 3-0
charcodes, 9-1
color, 10-0
colordvi, 10-0
commands
LATEX supported, 1-2
alternative files, 9-2
handling unsupported, 1-4
redefining, 9-4
renaming, 9-4
unknown, 9-3
unsupported, 1-4
compile, 2-0
conditionals, see \if
CSS, 12-7
definitions
delimited, 9-1
environments, 1-2
equations
textstyle, see in-line equations, overaccents
Error, 4-0
extensions to LATEX, B-0
flex, 2-0
font
face="symbol", 5-1
fonts, 1-1
footnotes, 9-4
frac command
see switch -L, B-0
gif, 6-4
graphics files, 6-4
HTML
3.2, 5-1
4.0, 5-1
insertion, 1-3
tags, B-0
icons, 6-4
\if, 1-1, 9-1
iftth, B-0
in-line equations
arrays, 5-2
built-up display, 5-2
fractions, 5-2
overaccents, 5-2
\includegraphics, 6-4
indexing, 6-3
\input
TEXINPUTS, 9-2
TTHINPUTS, 9-2
italic
equation style, 5-1
jpeg, 6-4
LaTeX2HTML
differences, 5-1, 6-1
limitations, 5-2
longtable, 7-3
Mac browsers, 12-1
macro files, 9-2
macros
alternate, 9-2
special use, A-0
makeindex, 6-3
mathematics, 1-1
messages, 4-0
Netscape Composer, 12-2
picture environment, 6-5
portability, 6-1
postscript, 6-4
printing, 12-5
ps2gif, 6-4
ps2png, 6-4
publish
through composer disallowed, 12-2
references
forward, 6-1
\rm, 1-1
spacing, 5-1
stderr, 3-0
stdin, 3-0
stdout, 3-0
style sheets, 12-7
switch
-L, B-0
switches
-L, 3-0, 6-1
TTH, 3-0
symbols, 12-3
Index entry, 6-3
tables
overwriting bug, 12-6
texinputs path, 9-2
title
HTML construction, 11-1
unknown commands, see commands, unknown
vertical alignment, 12-6
warning, 4-0
X fonts, 12-3

### Footnotes:

1The problem with \rm in text is that HTML has no < rm > tag, and relies on cancelling all previous (e.g.) < i > or < b > tags. TTHgold has a style switch -y that uses Cascading Style Sheets to solve this problem. However not all older browsers support CSS. The best solution is to avoid \rm by using proper grouping of non-roman text. (In equations \rm is essential, but TTH has a work-around in equations.)

2Conditionals \if and \ifx are not 100% TEX compatible for cases where they refer to internal TEX commands because TTH internals are not identical. Catcodes are also unknown to TTH.

3See appendix for TEX macros supporting these commands

4The PNG graphics file format is an improved replacement for the GIF standard. Netscape has built in rendering for PNG. The GIF standard is plagued with legal problems related to a ridiculous patent on the type of file compression it uses.

5May 1999 reports indicate that there is a batch program in circulation bearing the comment `:#batchified by cschenk@snafu.de'' that tries to implement the functionality of ps2gif and gives errors on WinNT when called by TTH but not when called from the command line. This problem appears to be related to memory management or other some operating system inadequacy. It would do everyone running on Wind*ws systems a favor if someone could figure out what the problem is and let me know at tth@hutchinson.belmont.ma.us. Meanwhile, it is reported that removing the pnmmargin command from the ps2gif batch file enables it to run. A Sep 99 report notes that on Win98 the pnmmargin command appears not to be available on the system. Remember, ps2gif is the user's responsibility.

6The alignment argument of the math array environment was ignored in TTH versions earlier than 2.20 but is now honored.

7See the file colordvi.tex for a list of the named colors.

File translated from TEX by TTHgold, version 2.77.
On 9 Sep 2000, 18:08.