The meta syntax uses the following conventions: `|' (bar) separates alternatives; `{' and `}' enclose optinal phrases; `{' and `}*' enclose phrases that may be repeated zero or more times; `{' and '}+' enclose phrases that must appear at least once and may be repeated; `<' and `>' enclose nonterminals.
<rcstext> ~~::=~~<admin> {<delta>}* <desc> {<deltatext>}*
<admin> ~~::=~~head ~~{<num>};
~~ ~~access ~~{<id>}*;
~~ ~~symbols ~~{<id> : <num>}*;
~~ ~~locks ~~{<id> : <num>}*;
~~ ~~comment ~~{<string>};
<delta> ~~::=~~<num>
~~ ~~date ~~<num>;
~~ ~~author ~~<id>;
~~ ~~state ~~{<id>};
~~ ~~branches ~~{<num>}*;
~~ ~~next ~~{<num>};
<desc> ~~::=~~desc ~~<string>
<deltatext>~~::=~~<num>
~~ ~~log ~~<string>
~~ ~~text ~~<string>
<num> ~~::=~~{<digit>{.}}+
<digit> ~~::=~~0 | 1 | ... | 9
<id> ~~::=~~<letter>{<idchar>}*
<letter> ~~::=~~A | B | ... | Z | a | b | ... | z
<idchar> ~~::=~~Any printing ASCII character except space,
~~ ~~tab, carriage return, new line, and <special>.
<special> ~~::=~~; | : | , | @
<string> ~~::=~~@{any ASCII character, with `@' doubled}*@
Identifiers are case sensitive. Keywords are in lower case only. The sets of keywords and identifiers may overlap.
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 decreasing numbers. The "head" field in the <admin> node points to the head of that sequence (i.e., contains the highest pair).
All <delta> nodes whose numbers consist of 2n fields (n>2) (e.g., 3.1.1.1, 2.1.2.2, etc.) are linked as follows. All nodes whose first (2n)-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-1) 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.
Example:
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\ \ / /1.2.2.1\
--------- \ / ---------
^ | ^
| | |
| v |
| --------- |
| \ 1.2 / |
----------------------\ /---------
\ /
\ /
|
|
v
---------
\ 1.1 /
\ /
\ /
\ /
Fig. 1: A revision tree
Revision Number: 3.0 ; Release Date: 82/11/18 .
Copyright © 1982 by Walter F. Tichy.