path: root/doc/xfpt.xfpt

.include stdflags
.include stdmacs

. We are going to type the name xfpt rather a lot. Make it easier:
.set X "<emphasis>xfpt</emphasis>"


. ----------------------------------------------------------------------------
.docbook
.book

.literal xml
<bookinfo>
<title>The xfpt plain text to XML processor</title>
<titleabbrev>xfpt</titleabbrev>
<date>18 May 2012</date>
<author>
  <firstname>Philip</firstname>
  <surname>Hazel</surname>
</author>
<authorinitials>PH</authorinitials>
<revhistory><revision><revnumber>0.09</revnumber><date>18 May 2012</date><authorinitials>PH</authorinitials></revision></revhistory>
<copyright><year>2012</year><holder>University of Cambridge</holder></copyright>
</bookinfo>
.literal off

. /////////////////////////////////////////////////////////////////////////////
. These lines are processing instructions for the Simple DocBook Processor that
. Philip Hazel has developed as a less cumbersome way of making PostScript and
. PDFs than using xmlto and fop. They will be ignored by all other XML
. processors.
. /////////////////////////////////////////////////////////////////////////////

.literal xml
<?sdop
  foot_right_recto="&chaptertitle;"
  foot_right_verso="&chaptertitle;"
?>
.literal off



. ----------------------------------------------------------------------------
.chapter "Introduction" ID00
&X; is a program that reads a marked-up ASCII source file, and converts it into
XML. It was written with DocBook XML in mind, but can also be used for other
forms of XML. Unlike &'AsciiDoc'& (&url(http://www.methods.co.nz/asciidoc/)),
&X; does not try to produce XML from a document that is also usable as a
freestanding ASCII document. The input for &X; is very definitely &"marked
up"&. This makes it less ambiguous for large and/or complicated documents. &X;
is also much faster than &'AsciiDoc'& because it is written in C and does not
rely on pattern matching.

&X; is aimed at users who understand the XML that they are generating. It makes
it easy to include literal XML, either in blocks, or within paragraphs. &X;
restricts itself to two special characters that trigger all its processing.

&X; treats any input line that starts with a dot as a &'directive'& line.
Directives control the way the input is processed. A small number of directives
are implemented in the program itself. A macro facility makes it possible to
combine these in various ways to define directives for higher-level concepts
such as chapters and sections. A standard macro library that generates a simple
subset of DocBook XML is provided. The only XML element that the program itself
generates is &`<para>`&; all the others must be included as literal XML, either
directly in the input text, or, more commonly, as part of the text that is
generated by a macro call.

The ampersand character is special within non-literal text that is processed by
&X;. An ampersand introduces a &'flag sequence'& that modifies the output.
Ampersand was chosen because it is also special in XML. As well as recognizing
flag sequences that begin with an ampersand, &X; converts grave accents and
apostrophes that appear in non-literal text into typographic opening and
closing quotes, as follows:

.display
 &`&nbsp;&#x60;    `&  becomes &nbsp;`
 &`&nbsp;&#x27;    `&  becomes &nbsp;'
.endd

Within normal input text, ampersand, grave accent, and apostrophe are the only
characters that cause &X; to change the input text, but this applies only to
non-literal text. In literal text, there are no markup characters, and only a
dot at the start of a line is recognized as special. Within the body of a
macro, there is one more special character: the dollar character is used to
introduce an argument substitution.

Notwithstanding the previous paragraph, &X; knows that it is generating XML,
and in all cases when a literal ampersand or angle bracket is required in the
output, the appropriate XML entity reference (&`&&amp;`&, &`&&lt;`&, or
&`&&gt;`&, respectively) is generated.


.section "The &X; command line" ID01
The format of the &X; command line is:
.display
 &`xfpt [`&&'options'&&`] [`&&'input source'&&`]`&
.endd
If no input is specified, the standard input is read. There are four options:

.vlist
.vitem &%-help%&
This option causes &X; to output its &"usage"& message, and exit.  
  
.vitem "&%-o%&&~&'<output destination>'&"
This option overrides the default destination. If the standard input is being
read, the default destination is the standard output. Otherwise, the default
destination is the name of the input file with the extension &_.xml_&,
replacing its existing extension if there is one. A single hyphen character can
be given as an output destination to refer to the standard output.

.vitem "&%-S%&&~&'<directory path>'&"
This option overrides the path to &X;'s library directory that is built into
the program. This makes it possible to use or test alternate libraries.

.vitem &%-v%&
This option causes &X; to output its version number and exit.
.endlist


.section "A short &X; example" ID02
Here is a very short example of a complete &X; input file that uses some of the
standard macros and flags:
.code
 .include stdflags
 .include stdmacs
 .docbook
 .book

 .chapter "The first chapter"
 This is the text of the first chapter. Here is an &'italic'&
 word, and here is a &*bold*& one.

 .section "This is a section heading"
 We can use the &*ilist*& macro to generate an itemized list:
 .ilist
 The first item in the list.
 .next
 The last item in the list.
 .endlist

 There are also standard macros for ordered lists, literal
 layout blocks, code blocks, URL references, index entries,
 tables, footnotes, figures, etc.
.endd



.section "Literal and non-literal processing" "SECTliteralprocessing" ID03
&X; processes non-directive input lines in one of four ways (known as
&"modes"&):

.ilist
In the default mode, text is processed paragraph by paragraph. 
.footnote
There is, however, a special case when a paragraph contains one or more 
footnotes. In that situation, each part of the outer paragraph is processed 
independently.
.endnote
The end of a paragraph is indicated by the end of the input, a blank line, or
by an occurrence of the &*.literal*& directive. Other directives (for example,
&*.include*&) do not of themselves terminate a paragraph. Most of the standard
macros (such as &*.chapter*& and &*.section*&) force a paragraph end by
starting their contents with a &*.literal*& directive.

Because &X; reads a whole paragraph before processing it, error messages
contain the phrase &"detected near line &'nnn'&"&, where the line number is
typically that of the last line of the paragraph.


.next
In the &"literal layout"& mode, text is processed line by line, but is
otherwise handled as in the default mode. The only real difference this makes
to the markup from the user's point of view is that both parts of a set of
paired flags must be on the same line. In this mode, error messages are more
likely to contain the exact line number where the fault lies. Literal layout
mode is used by the standard &*.display*& macro to generate &`<literallayout>`&
elements.

.next
In the &"literal text"& mode, text is also processed line by line, but no flags
are recognized. The only modification &X; makes to the text is to turn
ampersand and angle bracket characters into XML entity references. This mode is
used by the standard &*.code*& macro to generate &`<literallayout>`& elements
that include &`class=monospaced`&.

.next
In the &"literal XML"& mode, text lines are copied to the output without
modification. This is the easiest way to include a chunk of literal XML in the
output. An example might be the &`<bookinfo>`& element, which occurs only once
in a document. It is not worth setting up a macro for a one-off item like this.
.endlist

The &*.literal*& directive switches between the modes. It is not normally used
directly, but instead is incorported into appropriate macro definitions. The 
&*.inliteral*& directive can be used to test the current mode.

Directive lines are recognized and acted upon in all four modes. However, an
unrecognized line that starts with a dot in the literal text or literal XML
mode is treated as data. In the other modes, such a line provokes an error.

If you need to have a data line that begins with a dot in literal layout mode,
you can either specify it by character number, or precede it with some
non-acting markup. These two examples are both valid:
.code
 &#x2e;start with a dot
 &''&.start with a dot
.endd    
The second example assumes the standard flags are defined: it precedes the dot 
with an empty italic string. However, this is untidy because the empty string
will be carried over into the XML.

In literal text or literal XML mode, it is not possible to have a data line
that starts with a dot followed by the name of a directive or macro. You have
to use literal layout mode if you require such output. Another solution, which
is used in the source for this document (where many examples show directive
lines), is to indent every displayed line by one space, and thereby avoid the
problem altogether.


.section "Format of directive lines" ID04
If an input line starts with a dot followed by a space, it is ignored by &X;.
This provides a facility for including comments in the input. Otherwise, the
dot must be followed by a directive or macro name, and possibly one or more
arguments. Arguments that are strings are delimited by white space unless they
are enclosed in single or double quotes. The delimiting quote character can be
included within a quoted string by doubling it. Here are some examples:
.code
 .literal layout
 .set version 0.00
 .row "Jack's house" 'Jill''s house'
.endd
An unrecognized directive line normally causes an error; however, in the
literal text and literal XML modes, an unrecognized line that starts with a
dot is treated as a data line.



.section "Calling macros" "SECTcallingmacro" ID05
Macros are defined by the &*.macro*& directive, which is described in section
&<<SECTmacro>>&. There are two ways of calling a macro. It can be called in the
same way as a directive, or it can be called from within text that is being
processed. The second case is called an &"inline macro call"&.

When a macro is called as a directive, its name is given after a dot at the
start of a line, and the name may be followed by any number of optional
arguments, in the same way as a built-in directive (see the previous section).
For example:
.code
 .chapter "Chapter title" chapter-reference
.endd
The contents of the macro, after argument substitution, are processed in
exactly the same way as normal input lines. A macro that is called as a 
directive may contain nested macro calls.

When a macro is called from within a text string, its name is given after an
ampersand, and is followed by an opening parenthesis. Arguments, delimited by
commas, can then follow, up to a closing parenthesis. If an argument contains a
comma or a closing parenthesis, it must be quoted. White space after a
separating comma is ignored. The most common example of this type of macro
call is the standard macro for generating a URL reference:
.code
 Refer to a URL via &url(http://x.example,this text).
.endd

There are differences in the behaviour of macros, depending on which way they
are called. A macro that is called inline may not contain references to other
macros; it must contain only text lines and calls to built-in directives.
Also, newlines that terminate text lines within the macro are not included in
the output.

A macro that can be called inline can always be called as a directive, but the
opposite is not always true. Macros are usually designed to be called either
one way or the other. However, the &*.new*& and &*.index*& macros in the
standard library are examples of macros that are designed be called either way.





. ----------------------------------------------------------------------------
.chapter "Flag sequences" ID06
Only one flag sequence is built-into the code itself. If an input line ends
with three ampersands (ignoring trailing white space), the ampersands are
removed, and the next input line, with any leading white space removed, is
joined to the original line. This happens before any other processing, and may
involve any number of lines. Thus:

.display
 &`The quick &amp;&amp;&amp;`&
 &`    brown &amp;&amp;&amp;`&
 &`      fox.`&
.endd

produces exactly the same output as:

.code
 The quick brown fox.
.endd


.section "Flag sequences for XML entities and &X; variables" ID07
If an ampersand is followed by a # character, a number, and a semicolon, it is
understood as a numerical reference to an XML entity, and is passed through
unmodified. The number can be decimal, or hexadecimal preceded by &`x`&. For
example:
.code
 This is an Ohm sign: &#x2126;.
 This is a degree sign: &#176;.
.endd
If an ampersand is followed by a letter, a sequence of letters, digits, and
dots is read. If this is terminated by a semicolon, the characters between the
ampersand and the semicolon are interpreted as an entity name. This can be:
.ilist
The name of an inbuilt &X; variable. At present, there is only one of these,
called &`xfpt.rev`&. Its use is described with the &*.revision*& directive
below.
.next
The name of a user variable that has been set by the &*.set*& directive, also
described below.
.next
The name of an XML entity. This is assumed if the name is not recognized as one
of the previous types. In this case, the input text is passed to the output
without modification. For example:
.code
 This is an Ohm sign: &Ohm;.
.endd
.endlist


.section "Flag sequences for calling macros" ID08
If an ampersand is followed by a sequence of alphanumeric characters starting
with a letter, terminated by an opening parenthesis, the characters between the
ampersand and the parenthesis are interpreted as the name of a macro. See
section &<<SECTcallingmacro>>& for more details.



.section "Other flag sequences" ID09
Any other flag sequences that are needed must be defined by means of the
&*.flag*& directive. These are of two types, standalone and paired. Both cases
define replacement text. This is always literal; it is not itself scanned for
flag occurrences.

Lines are scanned from left to right when flags are being interpreted. If
there is any ambiguity when a text string is being scanned, the longest flag
sequence wins. Thus, it is possible (as in the standard flag sequences) to
define both &`&&<`& and &`&&<<`& as flags, provided that you never want to
follow the first of them with a &`<`& character.

You can define flags that start with &`&&#`&, but these must be used with care,
lest they be misinterpreted as numerical references to XML entities.

A standalone flag consists of an ampersand followed by any number of
non-alphanumeric characters. When it is encountered, it is replaced by its
replacement text. For example, in the standard flag definitions, &`&&&&`&
is defined as a standalone flag with with the replacement text &`&&amp;`&.

A paired flag is defined as two sequences. The first takes the same form as a
standalone flag. The second also consists of non-alphanumeric characters, but
need not start with an ampersand. It is often defined as the reverse of the
first sequence. For example, in the standard definitions, &`&&&#x27;`& and
&`&#x27;&&`& are defined as a flag pair for enclosing text in an &`<emphasis>`&
element.

When the first sequence of a paired flag is encountered, its partner is
expected to be found within the same text unit. In the default mode, the units
are a paragraphs, or part-paragraphs if footnotes intervene. In literal layout
mode, the text is processed line by line. Each member of the pair is replaced
by its replacement text. 

Multiple occurrences of paired flags must be correctly nested. Note that,
though &X; diagnoses an error for badly nested flag pairs, it does not prevent
you from generating invalid XML. For example, DocBook does not allow
&`<emphasis>`& within &`<literal>`&, though it does allow &`<literal>`& within
&`<emphasis>`&.


.section "Unrecognized flag sequences" ID10
If an ampersand is not followed by a character sequence in one of the forms
described in the preceding sections, an error occurs.


.section "Standard flag sequences" ID11
These are the standalone flag sequences that are defined in the &_stdflags_&
file in the &X; library:
.display
 &`&&&&        `& becomes &` &&amp;`& (ampersand)
 &`&&--       `& becomes &` &&ndash;`& (en-dash)
 &`&&~        `& becomes &` &&nbsp;`& (`hard' space)
.endd
These are the flag pairs that are defined in the &_stdflags_& file in the &X;
library:
.display
 &`&&"..."&&   `& becomes &`<quote>...</quote>`&
 &`&&&#x27;...&#x27;&&   `& becomes &`<emphasis>...</emphasis>`&
 &`&&*...*&&   `& becomes &`<emphasis role="bold">...</emphasis>`&
 &`&&&#x60;...&#x60;&&   `& becomes &`<literal>...</literal>`&
 &`&&_..._&&   `& becomes &`<filename>...</filename>`&
 &`&&(...)&&   `& becomes &`<command>...</command>`&
 &`&&[...]&&   `& becomes &`<function>...</function>`&
 &`&&%...%&&   `& becomes &`<option>...</option>`&
 &`&&$...$&&   `& becomes &`<varname>...</varname>`&
 &`&&<...>&&   `& becomes &`<...>`&
 &`&&<<...>>&& `& becomes &`<xref linkend="..."/>`&
.endd
For example, if you want to include a literal XML element in your output, you
can do it like this: &`&&<element>&&`&. If you want to include a longer
sequence of literal XML, changing to the literal XML mode may be more
convenient.




. ----------------------------------------------------------------------------
.chapter "Built-in directive processing" ID12
The directives that are built into the code of &X; are now described in
alphabetical order. You can see more examples of their use in the descriptions
of the standard macros in chapter &<<CHAPstdmac>>&.


.section "The &*.arg*& directive" ID13
This directive may appear only within the body of a macro. It must be followed
by a single number, optionally preceded by a minus sign. If the number is
positive (no minus sign), subsequent lines, up to a &*.endarg*& directive, are
skipped unless the macro has been called with at least that number of
arguments and the given argument is not an empty string. If the number is
negative (minus sign present), subsequent lines are skipped if the macro has
been called with fewer than that number of arguments, or with an empty string 
for the given argument. For example:
.code
 .macro example
 .arg 2
 Use these lines if there are at least 2 arguments 
 and the second one is not empty. Normally there would 
 be a reference to the 2nd argument. 
 .endarg
 .arg -2 
 Use this line unless there are at least 2 arguments 
 and the second one is not empty. 
 .endarg 
 .endmacro
.endd
Note that if a macro is defined with default values for its arguments, these
are not counted by the &*.arg*& directive, which looks only at the actual
arguments in a particular macro call.

The &*.arg*& directive may be nested.


.section "The &*.eacharg*& directive" ID14
This directive may appear only within the body of a macro. It may optionally be
followed by a single number; if omitted the value is taken to be 1. Subsequent
lines, up to a &*.endeach*& directive, are processed multiple times, once for
each remaining argument. Unlike &*.arg*&, an argument that is an empty string
is not treated specially. However, like &*.arg*&, only the actual arguments of
a macro call are considered. Default argument values do not count.

The number given with &*.eacharg*& defines which argument to start with. If the
macro is called with fewer arguments, the lines up to &*.endeach*& are skipped,
and are not processed at all. When these lines are being processed, the
remaining macro arguments can be referenced relative to the current argument.
&`$+1`& refers to the current argument, &`$+2`& to the next argument, and so
on.

The &*.endeach*& directive may also be followed by a number, again defaulting
to 1. When &*.endeach*& is reached, the current argument number is incremented
by that number. If there are still unused arguments available, the lines
between &*.eacharg*& and &*.endeach*& are processed again.

This example is taken from the coding for the standard &*.row*& macro, which
generates an &`<entry>`& element for each of its arguments:
.code
 .eacharg
 &<entry>&$+1&</entry>&
 .endeach
.endd
This example is taken from the coding for the standard &*.itable*& macro, which
processes arguments in pairs to define the table's columns, starting from the
fifth argument:
.code
 .eacharg 5
 &<colspec colwidth="$+1" align="$+2"/>&
 .endeach 2
.endd
The &*.eacharg*& directive may in principle be nested, though this does not 
seem useful in practice.


.section "The &*.echo*& directive" ID15
This directive takes a single string argument. It writes it to the standard
error stream. Within a macro, argument substitution takes place, but no other
processing is done on the string. This directive can be useful for debugging
macros or writing comments to the user.


.section "The &*.endarg*& directive" ID16
See the description of &*.arg*& above.


.section "The &*.endeach*& directive" ID17
See the description of &*.eacharg*& above.


.section "The &*.endinliteral*& directive" ID18
See the description of &*.inliteral*& below.


.section "The &*.flag*& directive" ID19
This directive is used to define flag sequences. The directive must be followed
either by a standalone flag sequence and one string in quotes, or by a flag
pair and two strings in quotes. White space separates these items. For example:
.code
 .flag && "&amp;"
 .flag &" "&  "<quote>"  "</quote>"
.endd
There are more examples in the definitions of the standard flags. If you
redefine an existing flag, the new definition overrides the old. There is no
way to revert to the previous definition.


.section "The &*.include*& directive" ID20
This directive must be followed by a single string argument that is the path to
a file. The contents of the file are read and incorporated into the input at
this point. If the string does not contain any slashes, the path to the &X;
library is prepended. Otherwise, the path is used unaltered. If 
&*.include*& is used inside a macro, it is evaluated each time the macro is 
called, and thus can be used to include a different file on each occasion.


.section "The &*.inliteral*& directive" ID21
This directive may appear only within the body of a macro. It must be followed 
by one of the words &"layout"&, &"text"&, &"off"&, or &"xml"&. If the current 
literal mode does not correspond to the word, subsequent lines, up to a 
&*.endinliteral*& directive, are skipped. The &*.inliteral*& directive may be
nested.


.section "The &*.literal*& directive" ID22
This must be followed by one of the words &"layout"&, &"text"&, &"off"&, or
&"xml"&. It forces an end to a previous paragraph, if there is one, and then
switches between processing modes. The default mode is the &"off"& mode, in
which text is processed paragraph by paragraph, and flags are recognized.
Section &<<SECTliteralprocessing>>& describes how input lines are processed in
the four modes.


.section "The &*.macro*& directive" "SECTmacro" ID23
This directive is used to define macros. It must be followed by a macro name,
and then, optionally, by any number of arguments. The macro name can be any
sequence of non-whitespace characters. The arguments in the definition provide
default values. The following lines, up to &*.endmacro*&, form the body of the
macro. They are not processed in any way when the macro is defined; they are
processed only when the macro is called (see section &<<SECTcallingmacro>>&).

Within the body of a macro, argument substitutions can be specified by means of
a dollar character and an argument number, for example, &`$3`& for the third
argument. See also &*.eacharg*& above for the use of &`$+`& to refer to
relative arguments when looping through them. A reference to an argument that
is not supplied, and is not given a default, results in an empty substitution.

There is also a facility for a conditional substitution. A reference to an
argument of the form:
.display
&`$=`&&'<digits><delimiter><text><delimiter>'&
.endd
inserts the text if the argument is defined and is not an empty string, and
nothing otherwise. The text is itself scanned for flags and argument
substitutions. The delimiter must be a single character that does not appear in
the text. For example:
.code
&<chapter$=2+ id="$2"+>&
.endd
If this appears in a macro that is called with only one argument, the result
is:
.code
<chapter>
.endd
but if the second argument is, say &`abcd`&, the result is:
.code
<chapter id="abcd">
.endd
This conditional feature can be used with both absolute and relative argument
references.

If a dollar character is required as data within the body of a macro, it must 
be doubled. For example:
.code
  .macro price
  The price is $$1.
  .endmacro
.endd     

If you redefine an existing macro, the new definition overrides the old. There
is no way to revert to the previous definition. If you define a macro whose 
name is the same as the name of a built-in directive you will not be able to 
call it, because &X; looks for built-in directives before it looks for macros.

It is possible to define a macro within a macro, though clearly care must be 
taken with argument references to ensure that substitutions happen at the right
level.


.section "The &*.nest*& directive" ID24
This directive must be followed by one of the words &"begin"& or &"end"&. It is
used to delimit a nested sequence of independent text items that occurs inside
another, such as the contents of a footnote inside a paragraph. This directive
is usually used inside a macro. For example, a &*footnote*& macro could be
defined like this:
.code
 .macro footnote
 &<footnote>&
 .nest begin
 .endmacro
.endd
At the start of a nested sequence, the current mode and paragraph state are
remembered and &X; then reverts to the default mode and &"not in a paragraph"&.
At the end of a nested sequence, if a paragraph has been started, it is
terminated, and then &X; reverts to the previous state.


.section "The &*.nonl*& directive" ID25
This directive must be followed by a single string argument. It is processed 
as an input line without a newline at the end. This facility is useful
in macros when constructing a single data line from several text fragments. See
for example the &*.new*& macro in the standard macros.


.section "The &*.pop*& directive" ID26
&X; keeps a stack of text strings that are manipulated by the &*.push*& and
&*.pop*& directives. When the end of the input is reached, any strings that
remain on the stack are popped off, processed for flags, and written to the
output. In some cases (see the &*.push*& directive below) a warning message is 
given.

Each string on the stack may, optionally, be associated with an upper case
letter. If &*.pop*& is followed by an upper case letter, it searches down the
stack for a string with the same letter. If it cannot find one, it does
nothing. Otherwise, it pops off, processes, and writes out all the strings down
to and including the one that matches.

If &*.pop*& is given without a following letter, it pops one string off the
stack and writes it out. If there is nothing on the stack, an error occurs.


.section "The &*.push*& directive" ID27
This directive pushes a string onto the stack. If the rest of the command line
starts with an upper case letter followed by white space or the end of the
line, that letter is associated with the string that is pushed, which consists
either of a quoted string, or the rest of the line. After a quoted string, the 
word `check' may appear. In this case, if the string has not been popped off 
the stack by the end of processing, a warning message is output. This facility 
is used by the standard macros to give warnings for unclosed items such as 
&*.ilist*&.

For example, the &*.chapter*& macro contains this line:
.code
 .push C &</chapter>&
.endd
Earlier in the macro there is the line:
.code
 .pop C
.endd
This arrangement ensures that any previous chapter is terminated before
starting a new one, and also when the end of the input is reached. The 
&*.ilist*& macro contains this line:
.code
 .push L "&</itemizedlist>&" check
.endd
Item lists are terminatated by &*.endlist*&, which contains:
.code
 .pop L
.endd  
However, if &*.endlist*& is accidentally omitted (or &*.ilist*& is accidentally
included), the appearance of `check' means that a warning is issued to alert 
the user to a possible problem.

.section "The &*.revision*& directive" "SECTrevision" ID28
This directive is provided to make it easy to set the &`revisionflag`&
attribute on XML elements in a given portion of the document. The DocBook
specification states that the &`revisionflag`& attribute is common to all
elements.

The &*.revision*& directive must be followed by one of the words &"changed"&,
&"added"&, &"deleted"&, or &"off"&. For any value other than &"off"&, it causes
the internal variable &'xfpt.rev'& to be set to &`revisionflag=`& followed by
the given argument. If the argument is &"off"&, the internal variable is
emptied.

The contents of &'xfpt.rev'& are included in every &`<para>`& element that &X;
generates. In addition, a number of the standard macros contain references to
&'xfpt.rev'& in appropriate places. Thus, setting:
.code
 .revision changed
.endd
should cause all subsequent text to be marked up with &`revisionflag`&
attributes, until
.code
 .revision off
.endd
is encountered. Unfortunately, at the time of writing, not all DocBook
processing software pays attention to the &`revisionflag`& attribute. 
Furthermore, some software grumbles that it is &"unexpected"& on some elements, 
though it does still seem to process it correctly.

For handling the most common case (setting and unsetting &"changed"&), the
standard macros &*.new*& and &*.wen*& are provided (see section
&<<SECTrevmacs>>&).


.section "The &*.set*& directive" ID29
This directive must be followed by a name and a text string. It defines a user
variable and gives it a name. A reference to the name in the style of an XML
entity causes the string to be substituted, without further processing. For
example:
.code
 .set version 4.99
.endd
This could be referenced as &`&&version;`&. If a variable is given the name of
an XML entity, you will not be able to refer to the XML entity, because local
variables take precedence. There is no way to delete a local variable after it
has been defined.



. ----------------------------------------------------------------------------
.chapter "The standard macros for DocBook" "CHAPstdmac" "Standard macros" ID30
A set of simple macros for commonly needed DocBook features is provided in
&X;'s library. This may be extended as experience with &X; accumulates. The
standard macros assume that the standard flags are defined, so a document that
is going to use these features should start with:
.code
 .include stdflags
 .include stdmacs
.endd
All the standard macros except &*new*&, &*index*&, and &*url*& are intended to
be called as directive lines. Their names are therefore shown with a leading
dot in the discussion below.

.section "Overall setup" ID31
There are two macros that should be used only once, at the start of the
document. The &*.docbook*& macro has no arguments. It inserts into the output
file the standard header material for a DocBook XML file, which is:
.code
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
.endd
The &*.book*& macro has no arguments. It generates &`<book>`& and pushes
&`</book>`& onto the stack so that it will be output at the end.


.section "Processing instructions"
XML processing instructions such as &`<?sdop`& &`toc_sections="no"?>`& can, of 
course, be written written literally between &`.literal`& &`xml`& and
&`.literal`& &`off`&. If there are a lot of them, this is perhaps the most
convenient approach. A macro called &*.pi*& is provided as an easy way of
setting up a short processing instruction. Its first argument is the name of
the processor for which the instruction is intended, and its second argument is
the contents of the instruction, for example:
.code
 .pi sdop 'toc_sections="yes,yes,no"'
.endd
This generates &`<?sdop`& &`toc_sections="yes,yes,no"?>`&.


.section "Chapters, sections, and subsections" ID32
Chapters, sections, and subsections are supported by three macros that all
operate in the same way. They are &*.chapter*&, &*.section*&, and
&*.subsection*&. They take either one, two, or three arguments. The first
argument is the title. If a second argument is present, and is not an empty
string, it is set as an ID, and can be used in cross-references. For example:
.code
 .chapter "Introduction"
.endd
sets no ID, but
.code
 .section "A section title" "SECTdemo"
.endd
can be referenced from elsewhere in the document by a phrase such as:
.code
 see section &<<SECTdemo>>&
.endd
When the title of a chapter of section is being used as a running head or foot 
(for example), it may be too long to fit comfortably into the available space. 
DocBook provides the facility for a title abbreviation to be specified to deal
with this problem. If a third argument is given to one of these macros, it
causes a &`<titleabbrev>`& element to be generated. In this case, a second
argument must also be provided, but if you do not need an ID, the second
argument can be an empty string. For example:
.code
  .chapter "This chapter has quite a long title" "" "Long title"
.endd   
Where and when the abbreviation is used in place of the full title is
controlled by the stylesheet when the XML is processed.


.section "Prefaces, appendixes, and colophons" ID33
The macros &*.preface*&, &*.appendix*&, and &*.colophon*& operate in the same 
way as &*.chapter*&, except that the first and the last have the default title
strings &"Preface"& and &"Colophon"&.


.section "Terminating chapters, etc."
The macros for chapters, sections, appendixes, etc. use the stack to ensure
that each one is terminated at the correct point, without the need for an 
explicit terminator. For example, starting a new section automatically
terminates an open subsection and a previous section.

Occasionally, however, there is a need to force an explicit termination. The
&*.endchapter*&, &*.endsection*&, &*.endsubsection*&, &*.endpreface*&,
&*.endappendix*&, and &*.endcolophon*& macros provide this facility. For
example, if you want to include an XML processing instruction after a preface,
but before the start of the following chapter, you must terminate the preface
with &*.endpreface*&. Otherwise a processing instruction that precedes the next
&*.chapter*& will end up inside the &`<preface>`& element. You should not 
include any actual text items at these points.



.section "URL references" ID34
The &*url*& macro generates URL references, and is intended to be called inline
within the text that is being processed. It generates a &`<ulink>`& element,
and has either one or two arguments. The first argument is the URL, and the
second is the text that describes it. For example:
.code
 More details are &url(http://x.example, here).
.endd
This generates the following XML:
.code
 More details are <ulink url="http://x.example">here</ulink>.
.endd
If the second argument is absent, the contents of the first argument are used
instead. If &*url*& is called as a directive, there will be a newline in the 
output after &`</ulink>`&, which in most cases (such as the example above), you 
do not want.



.section "Itemized lists" ID35
The &*.ilist*& macro marks the start of an itemized list, the items of which
are normally rendered with bullets or similar markings. The macro can
optionally be called with one argument, for which there is no default. If the
argument is present, it is used to add a &`mark=`& attribute to the
&`<itemizedlist>`& element that is generated. The mark names that can be used
depend on the software that processes the resulting XML. For HTML output,
&"square"& and &"opencircle"& work in some browsers.

The text for the first item follows the macro call. The start of the next item
is indicated by the &*.next*& macro, and the end of the list by &*.endlist*&.
For example:
.code
 .ilist
 This is the first item.
 .next
 This is the next item.
 .endlist
.endd
There may be more than one paragraph in an item. 


.section "Ordered lists" ID36
The &*.olist*& macro marks the start of an ordered list, the items of which are
numbered. If no argument is given, arabic numerals are used. One of the
following words can be given as the macro's argument to specify the numeration:
.display
&`arabic     `&   arabic numerals
&`loweralpha `&   lower case letters
&`lowerroman `&   lower case roman numerals
&`upperalpha `&   upper case letters
&`upperroman `&   upper case roman numerals
.endd
The text for the first item follows the macro call. The start of the next item
is indicated by the &*.next*& macro, and the end of the list by &*.endlist*&.
For example:
.code
 .olist lowerroman
 This is the first item.
 .next
 This is the next item.
 .endlist
.endd
There may be more than one paragraph in an item.


.section "Variable lists" ID37
A variable list is one in which each entry is composed of a set of one or more
terms and an associated description. Typically, the terms are printed in a
style that makes them stand out, and the description is indented underneath.
The start of a variable list is indicated by the &*.vlist*& macro, which has
one optional argument. If present, it defines a title for the list.

Each entry is defined by a &*.vitem*& macro, whose arguments are the terms.
This is followed by the body of the entry. The list is terminated by the
&*.endlist*& macro. For example:
.code
 .vlist "Font filename extensions"
 .vitem "TTF"
 TrueType fonts.
 .vitem "PFA" "PFB"
 PostScript fonts.
 .endlist
.endd
As for the other lists, there may be more than one paragraph in an item.


.section "Nested lists" ID38
Lists may be nested as required. Some DocBook processors automatically choose
different bullets for nested itemized lists, but others do not. The
&*.endlist*& macro has no useful arguments. Any text that follows it is
treated as a comment. This can provide an annotation facility that may make the
input easier to understand when lists are nested.


.section "Displayed text" ID39
In displayed text each non-directive input line generates one output line. The
&`<literallayout>`& DocBook element is used to achieve this. Two kinds of
displayed text are supported by the standard macros. They differ in their
handling of the text itself.

The macro &*.display*& is followed by lines that are processed in the same way
as normal paragraphs: flags are interpreted, and so there may be font changes
and so on. The lines are processed in literal layout mode. For example:
.code
 .display
 &`-o`&   set output destination
 &`-S`&   set library path
 .endd
.endd
The output is as follows:
.display
 &`-o`&   set output destination
 &`-S`&   set library path
.endd

The macro &*.code*& is followed lines that are not processed in any way, except
to turn ampersands and angle brackets into XML entities. The lines are
processed in literal text mode. In addition, &`class="monospaced"`& is added to
the &`<literallayout>`& element, so that the lines are displayed in a
monospaced font. For example:
.code
 .code
 z = sqrt(x*x + y*y);
 .endd
.endd

As the examples illustrate, both kinds of display are terminated by the
&*.endd*& macro.



.section "Block quotes" ID40
The macro pair &*.blockquote*& and &*.endblockquote*& are used to wrap the
lines between them in a &`<blockquote>`& element.


.section "Revision markings" "SECTrevmacs" ID41
Two macros are provided to simplify setting and unsetting the &"changed"&
revision marking (see section &<<SECTrevision>>&). When the revised text is
substantial (for example, a complete paragraph, table, display, or section), it
can be placed between &*.new*& and &*.wen*&, as in this example:
.code
  This paragraph is not flagged as changed.
  .new
  This is a changed paragraph that contains a display:
  .display
  whatever
  .endd
  This is the next paragraph.
  .wen      
  Here is the next, unmarked, paragraph.
.endd
When called like this, without an argument, in ordinary text, &*.new*&
terminates the current paragraph, and &*.wen*& always does so. Therefore, even
though there are no blank lines before &*.new*& or &*.wen*& above, the revised
text will end up in a paragraph of its own. (You can, of course, put in blank
lines if you wish.)

If want to indicate that just a few words inside a paragraph are revised, you
can call the &*new*& macro with an argument. The macro can be called either as
a directive or inline:
.code
  This is a paragraph that has 
  .new "a few marked words" 
  within it. Here are &new(some more) marked words.
.endd
The effect of this is to generate a &`<phrase>`& XML element with the
&`revisionflag`& attribute set. The &*.wen*& macro is not used in this case.

You can use the &*.new*&/&*.wen*& macro pair to generate a &`<phrase>`& element 
inside a section of displayed text. For example:
.code
  .display
  This line is not flagged as changed.
  .new
  This line is flagged as changed.
  .wen
  This line is not flagged as changed.
  .endd
.endd        
This usage works with both &*.display*& and &*.code*&. Within a &*.display*& 
section you can also call &*.new*& with an argument, either as a directive or 
inline. This does not work for &*.code*& because its lines are processed in
literal text mode.

If you want to add revision indications to part of a table, you must use an
inline call of &*new*& within an argument of the &*.row*& macro (see below).
This is the only usage that works in this case.


.section "Informal tables" ID42
The &*.itable*& macro starts an informal (untitled) table with some basic
parameterization. If you are working on a large document that has many tables
with the same parameters, the best approach is to define your own table macros,
possibly calling the standard one with specific arguments.

The &*.itable*& macro has four basic arguments:
.olist
The frame requirement for the table, which may be one of the words &"all"&,
&"bottom"&, &"none"& (the default), &"sides"&, &"top"&, or &"topbot"&.
.next
The &"colsep"& value for the table. The default is &"0"&, meaning no vertical
separator lines between columns. The value &"1"& requests vertical separator
lines.
.next
The &"rowsep"& value for the table. The default is &"0"&, meaning no horizontal
lines between rows. The value &"1"& requests horizontal separator lines.
.next
The number of columns.
.endlist
These arguments must be followed by two arguments for each column. The first
specifies the column width, and the second its aligmnent. A column width can be
specified as an absolute dimension such as 36pt or 2in, or as a proportional
measure, which has the form of a number followed by an asterisk. The two forms
can be mixed &-- see the DocBook specification for details.

Straightforward column alignments can be specified as &"center"&, &"left"&, or
&"right"&. DocBook also has some other possibilities, but sadly they do not 
seem to include &"centre"&.

Each row of the table is specified using a &*.row*& macro; the entries in
the row are the macros's arguments. The table is terminated by &*.endtable*&,
which has no arguments. For example:

.code
 .itable all 1 1 2 1in left 2in center
 .row "cell 11" "cell 12"
 .row "cell 21" "cell 22"
 .endtable
.endd

This specifies a framed table, with both column and row separator lines. There
are two columns: the first is one inch wide and left aligned, and the second is
two inches wide and centred. There are two rows. The resulting table looks like
this:

.itable all 1 1 2 1in left 2in center
.row "cell 11" "cell 12"
.row "cell 21" "cell 22"
.endtable

The &*.row*& macro does not set the &`revisionflag`& attribute in the 
&`<entry>`& elements that it generates because this appears to be ignored by 
all current XML processors. However, you can use an inline call of the &*new*& 
macro within an entry to generate a &`<phrase>`& element with &`revisionflag`& 
set.


.section "Formal tables" ID43
The &*.table*& macro starts a formal table, that is, a table that has a title, 
and which can be cross referenced. The first argument of this macro is the 
table's title; the second is an identifier for cross-referencing. If you are 
not going to reference the table, an empty string must be supplied. From the 
third argument onwards, the arguments are identical to the &*.itable*& macro.
For example:

.code
 .table "A title for the table" "" all 1 1 2 1in left 2in center
 .row "cell 11" "cell 12"
 .row "cell 21" "cell 22"
 .endtable
.endd


.section "Figures and images" ID44
A figure is enclosed between &*.figure*& and &*.endfigure*& macros. The first 
argument of &*.figure*& provides a title for the figure. The second is 
optional; if present, it is a tag for references to the figure.

A figure normally contains an image. The &*.image*& macro can be used in simple 
cases. It generates a &`<mediaobject>`& element containing an
&`<imageobject>`&. The first argument is the name of the file containing the
image. The remaining arguments are optional; an empty string must be
supplied as a placeholder when one that is not required is followed by one that
is set.

.ilist
The second argument specifies a scaling factor for the image, as a percentage. 
Thus, a value of 50 reduces the image to half size.
.next
The third argument specifies an alignment for the image. It must be one of 
&`left`& (default), &`right`& or &`center`& (or even &`centre`& if the
DocBook processor you are using can handle it).
.next
The fourth and fifth arguments specify the depth and width, respectively. How 
these values are handled depends on the processing software.
.endlist

Here is an example of the input for a figure, with all the image options 
defaulted:
.code
 .figure "My figure's title" "FIGfirst"
 .image figure01.eps
 .endfigure
.endd    

Here is another example, where the figure is reduced to 80% and centred:
.code
 .figure "A reduced figure"
 .image figure02.eps 80 center
 .endfigure  
.endd


.section "Footnotes" ID45
Footnotes can be specified between &*.footnote*& and &*.endnote*& macros. 
Within a footnote there can be any kind of text item, including displays and 
tables. When a footnote occurs in the middle of a paragraph, paired flags 
must not straddle the footnote. This example is wrong:
.code
 The &'quick
 .footnote
 That's really fast.
 .endf
 brown'& fox.
.endd
The correct markup for this example is:
.code
 The &'quick'&
 .footnote
 That's really fast.
 .endf
 &'brown'& fox.
.endd


.section "Indexes" ID46
The &*.index*& macro generates &`<indexterm>`& elements (index entries) in the
output. It takes one or two arguments. The first is the text for the primary
index term, and the second, if present, specifies a secondary index term. This
macro can be called either from a directive line, or inline. However, it is
mostly called as a directive, at the start of a relevant paragraph. For
example:
.code
 .index goose "wild chase"
 The chasing of wild geese...
.endd
You can generate &"see"& and &"see also"& index entries by using &*.index-see*& 
and &*.index-seealso*& instead of &*.index*&. The first argument of these 
macros is the text for the &"see"&. For example:
.code
 .index-see "chase" "wild goose"
.endd
This generates:
.code
 <indexterm>
 <primary>wild goose</primary>
 <see>chase</see>
 </indexterm>
.endd  

If you want to generate an index entry for a range of pages, you can use the 
&*.index-from*& and &*.index-to*& macros. The first argument of each of them is 
an ID that ties them together. The second and third arguments of 
&*.index-from*& are the primary and secondary index items. For example:
.code
 .index-from "ID5" "indexes" "handling ranges"
 ... <lines of text> ...
 .index-to "ID5"
.endd    

The &*.makeindex*& macro should be called at the end of the document, at the
point where you want an index to be generated. It can have up to two
arguments. The first is the title for the index, for which the default is
&"Index"&. The second, if present, causes a &`role=`& attribute to be added to
the &`<index>`& element that is generated. For this to be useful, you need to
generate &`<indexterm>`& elements that have similar &`role=`& attributes. The
standard &*index*& macro cannot do this. If you want to generate multiple
indexes using this mechanism, it is best to define your own macros for each
index type. For example:
.code
 .macro cindex
 &<indexterm role="concept">&
 &<primary>&$1&</primary>&
 .arg 2
 &<secondary>&$2&</secondary>&
 .endarg
 &</indexterm>&
 .endmacro
.endd
This defines a &*.cindex*& macro for the &"concept"& index. At the end of the 
document you might have:
.code
 .makeindex "Concept index" "concept"
 .makeindex
.endd
As long as the processing software can handle multiple indexes, this causes two
indexes to be generated. The first is entitled &"Concept index"&, and contains 
only those index entries that were generated by the &*.cindex*& macro. The 
second contains all index entries.

. === End ===