As might be inferred from the above, mom is two macro packages in one: a set of typesetting macros, and a set of document processing macros. The typesetting macros govern the physical aspects of page layout and provide sane, comprehensible control over typographic refinements. The document processing macros let you focus on a document's content and logical structure without worrying about typesetting or page layout at all.
Because mom provides both typesetting and document processing macros, it's safe to say she blurs the distinction between document processing and document design. While her basic document style comes with pretty spiffy defaults (okay--change "spiffy" to "typographically professional"), you can easily control how all the various document elements look: titles, page headers and footers, page numbering, heads, subheads, footnotes and so on can be made to come out exactly the way you want. And should you need precise typographic control over elements in a document that fall outside the range of mom's document element tags, you don't have to read up on groff primitives in order to accomplish what you want; the typesetting macros take care of that.
Typesetting with mom
Mom's typesetting macros control the basic parameters
of type: margins, line length, type family, font, point size,
linespacing, and so on. In addition, they allow you to move around
on the page horizontally and vertically, and to set up tabs, indents,
and columns. Finally, they let you adjust such typographic details as
justification style, letter spacing, word spacing, hyphenation, and
kerning.
In terms of typographic control, these macros resemble the commands used on dedicated typesetting computers like Compugraphics and Linotronics. Most of them simply give access to groff's typesetting primitives in a way that's consistent and easy to use. A few of them (tabs and indents, for example) handle fundamental typesetting requirements in ways radically different from groff primitives.
With mom's typesetting macros, you can, if you wish, create individual output pages that you design from the ground up. Provided you have not signalled to mom that you want document processing (via the START macro; see below), every macro is a literal command that remains in effect until you modify it or turn it off. This means that if you want to create flyers, surveys, tabulated forms, curricula vitae and so on, you may do so in the good old-fashioned way: one step at a time with complete control over every element on the page.
Years of reading various mailing lists dealing with computer typesetting (groff, TeX, and friends) have convinced me that no program can ever replace the human eye and human input when it comes to high quality typesetting. As of this writing, a thread on the subject of "micro typography" in groff has been going on for nearly a month. The reason for the lengthy thread is obvious; words and punctuation on the printed page are too variable, too fluid, to be rendered flawlessly by any algorithm, no matter how clever. (For whatever it's worth, a similar problem exists with engraving musical scores by computer.)
Mom does not try to solve the problems posed by things like hanging punctuation, left-margin adjustments for upper case letters like T and W, and so on. She merely tries to provide tools that allow knowledgeable typesetters to come up with solutions to these problems in ways that are easier and more intuitive than manipulating groff at the primitive level. As a professional typesetter of more than two decades, and a writer, I have encountered few situations that cannot be handled by mom's typesetting macros.
Author's note: One area where groff itself needs serious rethinking is in the matter of an algorithm that takes into account both word and letter spacing when justifying lines. At present, only word spacing is adjusted, requiring what I consider an unnecessary amount of user intervention whenever letter spacing is required.
Document processing with mom
Mom's document processing macros let you format
documents without having to worry about the typographic details.
In this respect, mom is similar to other groff macro
packages, as well as to html and LaTeX. Where mom
differs is in the degree of control you have over the look and
placement of the various elements of a document. For example, if you
don't want your heads underlined, or you want them bigger/smaller,
or you'd prefer them to be in a different font, or you'd rather they
were flush left instead of centred, you can make the changes easily
and have them apply to the whole document. Temporary and one-off
changes are easy, too.
Mom has some nifty features other macro sets don't provide. For example, you can switch between draft-style and final-copy output. If you regularly make submissions to publishers and editors who insist on "typewritten, double-spaced," there's a special macro-- PRINTSTYLE TYPEWRITE --that changes typeset documents into ones that would make your high-school typing teacher proud. Footnotes, endnotes, tables of contents, multiple columns, nested lists, recto/verso printing and user designable headers and footers are also part of the fun.
Mom's philosophy
Formatting documents should be easy, from soup to nuts. Writers need
to focus on what they're writing, not on how it looks. From the
moment you fire up an editor to the moment you add "FINIS"
to your opus, nothing should interfere with the flow of your words.
The commands needed to format your work should be easy to remember,
comprehensible, and stand out well from the text. There shouldn't
be too much clutter. Your documents should be as readable inside a
text editor as they are on the printed page.
Unfortunately, in computerland, "easy," "comprehensible," and "readable" often mean "you're stuck with what you get." No document formatting system can give you exactly what you want all the time, every time. Documents, it seems, always need to be tweaked, either to satisfy a typographic whim or to clarify some aspect of their content.
Groff has traditionally solved the problem of formatting vs. tweaking by requiring users of the common macro packages (mm, ms, me and their offspring) to resort to groff primitives and inline escapes for their special typesetting needs. Not to put too fine a point on it, groff primitives tend toward the abstruse, and most inline escapes are about as readable in-line as an encrypted password. This does not make for happy-camper writers, who either find themselves stuck with a document formatting style they don't really like, or are forced to learn groff from the ground up--a daunting task, to say the least.
Mom aims to make creating documents a simple matter, but with no corresponding loss of user control. The document processing macros provide an excellent set of defaults, but if something is not to your liking, you can change it. And in combination with the typesetting macros, you have all the tools you need to massage passages and tweak pages until they look utterly professional.
One rarely hears the word "user interface" in conjunction with document processing. Since the user formatting takes place inside a text editor, little thought is given to the look and feel of the formatting commands. Mom attempts to rectify this by providing users with a consistent, readable "coding" style. Most of the macros (especially in the document processing set) have humanly-readable names. Not only does this speed up learning the macros, it makes the sense of what's going on in a document, typographically and structurally, easier to decipher.
Mom does not try to be all things to all people. In contrast to the normal groff philosophy, she does not try to produce output that looks good no matter where it's displayed. She's designed for printed output, although with PRINTSTYLE TYPEWRITE she produces acceptable terminal copy. She makes no attempt to be compatible with older versions of troff.
One special feature in mom's design is the attention she pays to aligning the bottom margins of every page. Nothing screams "shoddy" in typeset documents louder than bottom margins that wander, or, in typesetter jargon, "hang." There are, of course, situations where whitespace at the bottom of a page may be desirable (for example, you wouldn't want a head to appear at the bottom of the page without some text underneath it), but in all cases where hanging bottom margins can be avoided, mom does avoid them, by clever adjustments to leading ("line spacing") and the spacing between different elements on the page.
A note on mom's documentation
Writing documentation is tough, no doubt about it. One is never
quite sure of the user's level of expertise. Is s/he new to the
application, new to its underlying protocols and programs, new to
the operating system, new to computers? At some point, one has to
decide who the documentation is for. Making the wrong decision can
mean the difference between a program that gets used and a program
that gets tossed.
Mom's documentation assumes users know their way
around GNU/Linux. It further assumes they at least know what groff
is, even if they don't know much about it. Lastly, it assumes that
everyone--groff newbies and experts alike--learns faster from
a few well-placed examples than from manpage-style reference docs.
What mom's documentation doesn't assume is that
you know everything--not about groff, not about typesetting,
not about document processing. Even experts have odd lacunae in
their knowledge base. Therefore, whenever I suspect that a term
or procedure will cause head scratching, I offer an explanation.
And when explanations aren't enough, I offer examples.
Canonical reference materials
The canonical reference materials for groff are cstr54 (a downloadable PostScript copy of which is available here) and the troff and groff_diff manpages. Another excellent source of information (maybe the best) is the groff info pages, available by typing
info groffat the command line (assuming you have info installed on your system). And for inputting special characters, see man groff_char.
I've tried to avoid reiterating the information contained in these documents; however, in a few places, this has proved impossible. But be forewarned: I have no qualms about sidestepping excruciating completeness concerning groff usage; I'm more interested in getting mom users up and running. Mea culpa.
Note: Mom's macro file (om.tmac) is heavily commented. Each macro is preceded by a description of its arguments, function and usage, which may give you information in addition to what's contained in this documentation.
How to read macro arguments
The concise descriptions of macros in this documentation typically
look like this:
Macro: NAMEarguments lists the macro's arguments using conventions that should be familiar to anyone who has ever read a manpage. Briefly:arguments
Some macros don't require an argument. They simply start something. When you need to turn them off, the same macro with any argument will do the trick. That's right: ANY argument. This permits choosing whatever works for you: OFF, END, QUIT, DONE, Q, X... Hell, it could even be I_LOVE_MOM.
Since these macros toggle things on and off, the argument list simply reads
toggle
Macro: TITLE"<title of document>"
The required argument to TITLE is the title of your document. Since it's surrounded by double-quotes, you must include them in the argument, like this:
.TITLE "My Pulitzer Novel"
Macro: TAB_SET<tab #> <indent> <length> [ L | R | C | J [ QUAD ] ]
The first required argument is a number that identifies the tab (say, "3"). The second required argument is an indent from the left margin (say, 6 picas). The third required argument is the length of the tab (say, 3 picas). Therefore, at a minimum, when using this macro, you would enter:
.TAB_SET 3 6P 3PThe remaining two arguments are optional. The first is a single letter, either L, R, C or J. The second, which is itself optional after L, R, C or J, is the word QUAD. Therefore, depending on what additional information you wish to pass to the macro, you could enter:
.TAB_SET 3 6P 3P L or .TAB_SET 3 6P 3P L QUAD
Macro: QUOTEtoggle
QUOTE begins a section of quoted text in a document and doesn't require an argument. When the quote's finished, you have to tell mom it's done.
.QUOTE So runs my dream, but what am I? An infant crying in the night An infant crying for the light And with no language but a cry. .QUOTE OFFAlternatively, you could have turned the quote off with END, or X, or something else.