add version number format note to perldelta

diff --git a/pod/perl5114delta.pod b/pod/perl5114delta.pod
index d6c5974..d9f3276 100644 (file)
--- a/pod/perl5114delta.pod
+++ b/pod/perl5114delta.pod
@@ -22,6 +22,26 @@ XXX For a release on a stable branch, this section aspires to be:
     There are no changes intentionally incompatible with 5.XXX.XXX. If any
     exist, they are bugs and reports are welcome.
 
+=head2 Version number formats
+
+Acceptable version number formats have been formalized into "strict" and
+"lax" rules.  C<package NAME VERSION> takes a strict version number.  C<use
+NAME VERSION> takes a lax version number.  C<UNIVERSAL::VERSION> and the
+L<version> object constructors take lax version numbers.  Providing an
+invalid version will result in a fatal error.
+
+These formats will be documented fully in the L<version> module in a
+subsequent release of Perl 5.11.  To a first approximation, a "strict"
+version number is a positive decimal number (integer or decimal-fraction)
+without exponentiation or else a dotted-decimal v-string with a leading 'v'
+character and at least three components.  A "lax" version number allows
+v-strings with fewer than three components or without a leading 'v'.  Under
+"lax" rules, both decimal and dotted-decimal versions may have a trailing
+"alpha" component separated by an underscore character after a fractional
+or dotted-decimal component.
+
+The L<version> module adds C<version::is_strict> and C<version::is_lax>
+functions to check a scalar against these rules.
 
 =head1 Core Enhancements