1RCSFILE(5) File Formats Manual RCSFILE(5)
2
6 rcsfile - RCS file format
7
9 An RCS file's contents are described by the grammar below.
10 The text is free format: space, backspace, tab, newline, vertical tab,
12 form feed, and carriage return (collectively, white space) have no sig‐
13 nificance except in strings. However, white space cannot appear within
14 an id, num, or sym, and an RCS file must end with a newline.
15 Strings are enclosed by @. If a string contains a @, it must be dou‐
17 bled; otherwise, strings can contain arbitrary binary data.
18 The meta syntax uses the following conventions: `|' (bar) separates
20 alternatives; `{' and `}' enclose optional phrases; `{' and `}*'
21 enclose phrases that can be repeated zero or more times; `{' and '}+'
22 enclose phrases that must appear at least once and can be repeated;
23 Terminal symbols are in boldface; nonterminal symbols are in italics.
24 rcstext ::= admin {delta}* desc {deltatext}*
26 admin ::= head {num};
28 { branch {num}; }
29 access {id}*;
30 symbols {sym : num}*;
31 locks {id : num}*; {strict ;}
32 { integrity{intstring}; }
33 { comment {string}; }
34 { expand {string}; }
35 delta ::= num
37 date num;
38 author id;
39 state {id};
40 branches {num}*;
41 next {num};
42 { commitid sym; }
43 desc ::= desc string
45 deltatext ::= num
47 log string
48 text string
49 num ::= {digit | .}+
51 digit ::= 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
53 id ::= {idchar | .}+
55 sym ::= {idchar}+
57 idchar ::= any visible graphic character except special
59 special ::= $ | , | . | : | ; | @
61 string ::= @{any character, with @ doubled}*@
63 word ::= id | num | string | :
65 intchar ::= any character, except @
67 thirdp ::= ^L {intchar}*
69 intstring ::= @ {intchar}* {thirdp}* @
71 In releases prior to 5.8 (2011-08-30), the grammar included the new‐
73 phrase production and used it in the admin, delta and deltatext produc‐
74 tions. This allowed third-party programs to interoperate with RCS by
75 storing opaque (to RCS) data in the file. As of 5.8, in the name of
76 progress (towards more systematic file integrity support), the only
77 area reserved for third-party interop is in the (string) value of the
78 integrity field, specifically after the first ^L (formfeed). A further
79 restriction (for all programs) is that the integrity value must not
80 contain @.
81 Identifiers are case sensitive. Keywords are in lower case only. The
83 sets of keywords and identifiers can overlap. In most environments RCS
84 uses the ISO 8859/1 encoding: visible graphic characters are codes
85 041-176 and 240-377, and white space characters are codes 010-015 and
86 040.
87 Dates, which appear after the date keyword, are of the form
89 Y.mm.dd.hh.mm.ss, where Y is the year, mm the month (01-12), dd the day
90 (01-31), hh the hour (00-23), mm the minute (00-59), and ss the second
91 (00-60). Y contains just the last two digits of the year for years
92 from 1900 through 1999, and all the digits of years thereafter. Dates
93 use the Gregorian calendar; times use UTC.
94 The delta nodes form a tree. All nodes whose numbers consist of a sin‐
96 gle pair (e.g., 2.3, 2.1, 1.3, etc.) are on the trunk, and are linked
97 through the next field in order of decreasing numbers. The head field
98 in the admin node points to the head of that sequence (i.e., contains
99 the highest pair). The branch node in the admin node indicates the
100 default branch (or revision) for most RCS operations. If empty, the
101 default branch is the highest branch on the trunk.
102 All delta nodes whose numbers consist of 2n fields (n≥2) (e.g.,
104 3.1.1.1, 2.1.2.2, etc.) are linked as follows. All nodes whose first
105 2n-1 number fields are identical are linked through the next field in
106 order of increasing numbers. For each such sequence, the delta node
107 whose number is identical to the first 2n-2 number fields of the deltas
108 on that sequence is called the branchpoint. The branches field of a
109 node contains a list of the numbers of the first nodes of all sequences
110 for which it is a branchpoint. This list is ordered in increasing num‐
111 bers.
112 The following diagram shows an example of an RCS file's organization.
114 Head
116 |
117 |
118 v / \
119 --------- / \
120 / \ / \ | | / \ / \
121 / \ / \ | 2.1 | / \ / \
122 / \ / \ | | / \ / \
123 /1.2.1.3\ /1.3.1.1\ | | /1.2.2.2\ /1.2.2.1.1.1\
124 --------- --------- --------- --------- -------------
125 ^ ^ | ^ ^
126 | | | | |
127 | | v | |
128 / \ | --------- / \ |
129 / \ | \ 1.3 / / \ |
130 / \ ---------\ / / \-----------
131 /1.2.1.1\ 1.3.1 \ / /1.2.2.1\ 1.2.2.1.1
132 --------- \ / ---------
133 ^ | ^
134 | | |
135 | v |
136 | --------- |
137 | \ 1.2 / |
138 ----------------------\ /---------
139 1.2.1 \ / 1.2.2
140 \ /
141 |
142 |
143 v
144 ---------
145 \ 1.1 /
146 \ /
147 \ /
148 \ /
149
152 Author: Walter F. Tichy.
153 Manual Page Revision: 5.10.0; Release Date: 2020-12-08.
154 Copyright © 2010-2020 Thien-Thi Nguyen.
155 Copyright © 1990, 1991, 1992, 1993, 1994, 1995 Paul Eggert.
156 Copyright © 1982, 1988, 1989 Walter F. Tichy.
157
159 ci(1), co(1), ident(1), rcs(1), rcsclean(1), rcsdiff(1), rcsmerge(1),
160 rlog(1).
161 Walter F. Tichy, RCS--A System for Version Control, Software--Practice
163 & Experience 15, 7 (July 1985), 637-654.
164 The full documentation for RCS is maintained as a Texinfo manual. If
166 the info(1) and RCS programs are properly installed at your site, the
167 command
168 info rcs
170 should give you access to the complete manual. Additionally, the RCS
172 homepage:
173 http://www.gnu.org/software/rcs/
175 has news and links to the latest release, development site, etc.
177GNU RCS 5.10.0 2020-12-08 RCSFILE(5)