Annotation of mandoc/eqn.7, Revision 1.6
1.6 ! kristaps 1: .\" $Id: eqn.7,v 1.5 2011/07/21 10:24:35 kristaps Exp $
1.1 kristaps 2: .\"
3: .\" Copyright (c) 2011 Kristaps Dzonsons <kristaps@bsd.lv>
4: .\"
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1.6 ! kristaps 17: .Dd $Mdocdate: July 21 2011 $
1.1 kristaps 18: .Dt EQN 7
19: .Os
20: .Sh NAME
21: .Nm eqn
22: .Nd eqn language reference for mandoc
23: .Sh DESCRIPTION
24: The
25: .Nm eqn
26: language is a equation-formatting language.
27: It is used within
28: .Xr mdoc 7
29: and
30: .Xr man 7
31: .Ux
32: manual pages.
33: This manual describes the subset of the
34: .Nm
35: language accepted by the
36: .Xr mandoc 1
37: utility.
38: .Pp
39: Equations within
40: .Xr mdoc 7
41: or
42: .Xr man 7
1.3 kristaps 43: documents are enclosed by the standalone
44: .Sq \&.EQ
1.1 kristaps 45: and
1.3 kristaps 46: .Sq \&.EN
47: tags.
48: Equations are multi-line blocks consisting of formulas and control
49: statements.
50: .Sh EQUATION STRUCTURE
51: Each equation is bracketed by
52: .Sq \&.EQ
53: and
54: .Sq \&.EN
55: strings.
56: .Em Note :
57: these are not the same as
58: .Xr roff 7
59: macros, and may only be invoked as
60: .Sq \&.EQ .
61: .Pp
62: The equation grammar is as follows:
63: .Bd -literal -offset indent
64: eqn : box | eqn box
65: box : text
66: | DEFINE text text
67: | SET text text
68: | UNDEF text
69: text : TEXT
70: .Ed
71: .Pp
72: Data in TEXT form is a non-empty sequence of non-space characters or a
73: non-empty quoted string.
1.5 kristaps 74: Unless within a quoted string, white-space (and enclosing literal quote
75: pairs) is thrown away.
1.6 ! kristaps 76: Quoted strings are not scanned for replacement definitions.
1.3 kristaps 77: .Pp
78: The following control statements are available:
79: .Bl -tag -width Ds
80: .It Cm define
81: Replace all occurances of a key with a value.
82: Its syntax is as follows:
83: .Pp
1.5 kristaps 84: .D1 define Ar key cvalc
85: .Pp
86: The first character of the value string,
87: .Ar c ,
88: is used as the delimiter for the value
89: .Ar val .
90: This allows for arbitrary enclosure of terms (not just quotes), such as
91: .Pp
92: .D1 define Ar foo 'bar baz'
93: .D1 define Ar foo cbar bazc
1.2 kristaps 94: .Pp
1.3 kristaps 95: It is an error to have an empty
96: .Ar key or
1.5 kristaps 97: .Ar val .
1.3 kristaps 98: Note that a quoted
99: .Ar key
100: causes errors in some
1.2 kristaps 101: .Nm
1.3 kristaps 102: implementations and should not be considered portable.
1.4 kristaps 103: Definitions may refer to other definitions; these are evaluated
104: recursively when text replacement occurs and not when the definition is
105: created.
1.5 kristaps 106: .Pp
107: Definitions can create arbitrary strings, for example, the following is
108: a legal construction.
109: .Bd -literal -offset indent
110: define foo 'define'
111: foo bar 'baz'
112: .Ed
113: .Pp
1.4 kristaps 114: Self-referencing definitions will raise an error.
1.3 kristaps 115: .It Cm set
1.4 kristaps 116: Set an equation mode.
1.3 kristaps 117: Both arguments are thrown away.
118: .It Cm undef
119: Unset a previously-defined key.
120: Its syntax is as follows:
121: .Pp
122: .D1 define Ar key
1.2 kristaps 123: .Pp
1.3 kristaps 124: Once invoked, the definition for
125: .Ar key
126: is discarded.
127: .El
1.5 kristaps 128: .Sh COMPATIBILITY
129: This section documents the compatibility of mandoc
130: .Nm
131: and the troff
132: .Nm
133: implementation (including GNU troff).
134: .Pp
135: .Bl -dash -compact
136: .It
137: The text string
138: .Sq \e\*q
139: is interpreted as a literal quote in troff.
140: In mandoc, this is interpreted as a comment.
141: .El
1.1 kristaps 142: .Sh SEE ALSO
143: .Xr mandoc 1 ,
144: .Xr man 7 ,
145: .Xr mandoc_char 7 ,
146: .Xr mdoc 7 ,
147: .Xr roff 7
148: .Rs
149: .%A Brian W. Kernighan
150: .%A Lorinda L. Cherry
151: .%T System for Typesetting Mathematics
152: .%J Communications of the ACM
153: .%V 18
154: .%P 151\(en157
155: .%D March, 1975
156: .Re
1.5 kristaps 157: .Rs
158: .%A Brian W. Kernighan
159: .%A Lorinda L. Cherry
160: .%T Typesetting Mathematics, User's Guide
161: .%D 1976
162: .Re
163: .Rs
164: .%A Brian W. Kernighan
165: .%A Lorinda L. Cherry
166: .%T Typesetting Mathematics, User's Guide (Second Edition)
167: .%D 1978
168: .Re
169: .Sh HISTORY
170: The eqn utility, a preprocessor for troff, was originally written by
171: Brian W. Kernighan and Lorinda L. Cherry in 1975.
172: The GNU reimplementation of eqn, part of the GNU troff package, was
173: released in 1989 by James Clark.
174: The eqn component of
175: .Xr mandoc 1
176: was added in 2011.
1.1 kristaps 177: .Sh AUTHORS
1.5 kristaps 178: This
1.1 kristaps 179: .Nm
180: reference was written by
181: .An Kristaps Dzonsons Aq kristaps@bsd.lv .
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