# rcsfile(5) - man - phpMan [RCSFILE(5)](https://www.chedong.com/phpMan.php/man/RCSFILE/5/markdown) File Formats Manual [RCSFILE(5)](https://www.chedong.com/phpMan.php/man/RCSFILE/5/markdown) ## NAME rcsfile - RCS file format ## DESCRIPTION An RCS file's contents are described by the grammar below. The text is free format: space, backspace, tab, newline, vertical tab, form feed, and car‐ riage return (collectively, _white_ _space_) have no significance except in strings. However, white space cannot appear within an id, num, or sym, and an RCS file must end with a newline. Strings are enclosed by **@**. If a string contains a **@**, it must be doubled; otherwise, strings can contain arbitrary binary data. The meta syntax uses the following conventions: `|' (bar) separates alternatives; `{' and `}' enclose optional phrases; `{' and `}*' enclose phrases that can be repeated zero or more times; `{' and '}+' enclose phrases that must appear at least once and can be repeated; Ter‐ minal symbols are in **boldface**; nonterminal symbols are in _italics_. _rcstext_ ::= _admin_ {_delta_}* _desc_ {_deltatext_}* _admin_ ::= **head** {_num_}**;** { **branch** {_num_}**;** } **access** {_id_}***;** **symbols** {_sym_ **:** _num_}***;** **locks** {_id_ **:** _num_}***;** {**strict** **;**} { **integrity**{_intstring_}**;** } { **comment** {_string_}**;** } { **expand** {_string_}**;** } _delta_ ::= _num_ **date** _num_**;** **author** _id_**;** **state** {_id_}**;** **branches** {_num_}***;** **next** {_num_}**;** { **commitid** _sym_**;** } _desc_ ::= **desc** _string_ _deltatext_ ::= _num_ **log** _string_ **text** _string_ _num_ ::= {_digit_ | **.**}+ _digit_ ::= **0** | **1** | **2** | **3** | **4** | **5** | **6** | **7** | **8** | **9** _id_ ::= {_idchar_ | **.**}+ _sym_ ::= {_idchar_}+ _idchar_ ::= any visible graphic character except _special_ _special_ ::= **$** | **,** | **.** | **:** | **;** | **@** _string_ ::= **@**{any character, with **@** doubled}***@** _word_ ::= _id_ | _num_ | _string_ | **:** _intchar_ ::= any character, except **@** _thirdp_ ::= **^L** {_intchar_}* _intstring_ ::= **@** {_intchar_}* {_thirdp_}* **@** In releases prior to 5.8 (2011-08-30), the grammar included the _newphrase_ production and used it in the _admin_, _delta_ and _deltatext_ productions. This allowed third-party programs to in‐ teroperate with RCS by storing opaque (to RCS) data in the file. As of 5.8, in the name of progress (towards more systematic file integrity support), the only area reserved for third- party interop is in the (string) value of the _integrity_ field, specifically after the first ### ^L (formfeed) contain **@**. Identifiers are case sensitive. Keywords are in lower case only. The sets of keywords and identifiers can overlap. In most environments RCS uses the ISO 8859/1 encoding: visible graphic characters are codes 041-176 and 240-377, and white space characters are codes 010-015 and 040. Dates, which appear after the **date** keyword, are of the form _Y_**.**_mm_**.**_dd_**.**_hh_**.**_mm_**.**_ss_, where _Y_ is the year, _mm_ the month (01-12), _dd_ the day (01-31), _hh_ the hour (00-23), _mm_ the minute (00-59), and _ss_ the second (00-60). _Y_ contains just the last two digits of the year for years from 1900 through 1999, and all the digits of years thereafter. Dates use the Gregorian calendar; times use UTC. The _delta_ nodes form a tree. All nodes whose numbers consist of a single pair (e.g., 2.3, 2.1, 1.3, etc.) are on the trunk, and are linked through the **next** field in order of decreas‐ ing numbers. The **head** field in the _admin_ node points to the head of that sequence (i.e., contains the highest pair). The **branch** node in the admin node indicates the default branch (or revision) for most RCS operations. If empty, the default branch is the highest branch on the trunk. All _delta_ nodes whose numbers consist of 2_n_ fields (_n_≥2) (e.g., 3.1.1.1, 2.1.2.2, etc.) are linked as follows. All nodes whose first 2_n_-1 number fields are identical are linked through the **next** field in order of increasing numbers. For each such sequence, the _delta_ node whose number is identical to the first 2_n_-2 number fields of the deltas on that sequence is called the branchpoint. The **branches** field of a node contains a list of the numbers of the first nodes of all sequences for which it is a branchpoint. This list is ordered in increasing numbers. The following diagram shows an example of an RCS file's organization. Head | | v / \ --------- / \ / \ / \ | | / \ / \ / \ / \ | 2.1 | / \ / \ / \ / \ | | / \ / \ /1.2.1.3\ /1.3.1.1\ | | /1.2.2.2\ /1.2.2.1.1.1\ --------- --------- --------- --------- ------------- ^ ^ | ^ ^ | | | | | | | v | | / \ | --------- / \ | / \ | \ 1.3 / / \ | / \ ---------\ / / \----------- /1.2.1.1\ 1.3.1 \ / /1.2.2.1\ 1.2.2.1.1 --------- \ / --------- ^ | ^ | | | | v | | --------- | | \ 1.2 / | ----------------------\ /--------- 1.2.1 \ / 1.2.2 \ / | | v --------- \ 1.1 / \ / \ / \ / ## IDENTIFICATION Author: Walter F. Tichy. Manual Page Revision: 5.10.1; Release Date: 2022-02-19. Copyright © 2010-2022 Thien-Thi Nguyen. Copyright © 1990, 1991, 1992, 1993, 1994, 1995 Paul Eggert. Copyright © 1982, 1988, 1989 Walter F. Tichy. ## SEE ALSO [**ci**(1)](https://www.chedong.com/phpMan.php/man/ci/1/markdown), [**co**(1)](https://www.chedong.com/phpMan.php/man/co/1/markdown), [**ident**(1)](https://www.chedong.com/phpMan.php/man/ident/1/markdown), [**rcs**(1)](https://www.chedong.com/phpMan.php/man/rcs/1/markdown), [**rcsclean**(1)](https://www.chedong.com/phpMan.php/man/rcsclean/1/markdown), [**rcsdiff**(1)](https://www.chedong.com/phpMan.php/man/rcsdiff/1/markdown), [**rcsmerge**(1)](https://www.chedong.com/phpMan.php/man/rcsmerge/1/markdown), [**rlog**(1)](https://www.chedong.com/phpMan.php/man/rlog/1/markdown). Walter F. Tichy, RCS--A System for Version Control, _Software--Practice_ _&_ _Experience_ **15**, 7 (July 1985), 637-654. The full documentation for RCS is maintained as a Texinfo manual. If the [**info**(1)](https://www.chedong.com/phpMan.php/man/info/1/markdown) and RCS programs are properly installed at your site, the command **info** **rcs** should give you access to the complete manual. Additionally, the RCS homepage: **** has news and links to the latest release, development site, etc. GNU RCS 5.10.1 2022-02-19 [RCSFILE(5)](https://www.chedong.com/phpMan.php/man/RCSFILE/5/markdown)