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In Project Tree Inventories, you learned how the tla
inventory
 command classifies files within a project tree using a set
of naming conventions.   This appendix explains how you can customize
those naming conventions.
It's best to make customizations to the naming conventions of a
project at the outset: before you import
 your first revision.
If you must make changes later, then it's essential that your changes do not change the classification of files already in the latest revision(s) of your project at the time you make the change (otherwise, you are likely to experience perplexing and undesirable behavior).
You should begin by reviewing the naming convention algorithm in The arch Naming Conventions. You can modify that algorithm by changing the regular expression used for each category test.
You can customize naming conventions by modifying the file
./{arch}/=tagging-method
 in your project trees.  That file is created
by the id-tagging-method
 command and initially, it contains a single
line which names the id tagging method (names
, explicit
, tagline
(or the now deprecated, but popular in some older projects, including
arch itself, implicit
)).
In particular, =tagging-method
 can contain blank lines and comments
(lines beginning with 
#
) and directives, one per line.  The
permissible directives are:
        tagline
        implicit
        explicit
        names
                specify the id tagging method to use for this tree
        exclude RE
        junk RE
        backup RE
        precious RE
        unrecognized RE
        source RE
                specify a regular expression to use for the indicated
                category of files.
Regular expressions are specified in Posix ERE syntax (the same syntax used by egrep , grep -E , and awk ) and have default values which implement the naming conventions described in The arch Naming Conventions.
A given regexp directive can occur more than once, in which case the regexps are concatenated as alternatives. Thus, for example:
        source  .*\.c$
        source  .*\.h$
is equivalent to:
        source (.*\.c$)|(.*\.h$)
A source directory can contain a .arch-inventory
 file.
.arch-inventory
 files can contain regexp declarations just like
those in =tagging-method (i.e., one for excludes
, one for
junk
, etc.)   Let's call these the 
dir-local regexps
.
The =tagging-method
 regexps are the 
global regexps
.
While traversing a tree, each file is classified-by-name as follows.
the steps which are changed by .arch-inventory
 are marked with
[*]
:
        0) "." and ".." remain excluded files, no matter what.
   [*]  1) if excluded files are being omitted from the inventory,
           and either the dir-local or global regexp, the file
           is excluded
        2) if the file is a control file, it is source
        3) if the file falls into one of the "mandatory categories"
           (",," and "++" files) it is categorized as junk or 
           precious respectively.
   [*]  4) the dir-local (only) regexps are tried in the usual order:
           junk, backup, precious, unrecognized, source.  If the file
           matches, it is suitably categorized.
        5) the global regexps are tried in the same order.
        6) otherwise the file is unrecognized.
arch Meets hello-world: A Tutorial Introduction to The arch Revision Control System
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