use YAPE::Regex::Explain;
print YAPE::Regex::Explain->new( '/^v[0-9][0-9]\.[0-9][0-9]-[a-z][0-9][0-9][0-9]/' )->explain;
__END__
The regular expression:

(?-imsx:/^v[0-9][0-9]\.[0-9][0-9]-[a-z][0-9][0-9][0-9]/)

matches as follows:

NODE                     EXPLANATION
----------------------------------------------------------------------
(?-imsx:                 group, but do not capture (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
                         normally):
----------------------------------------------------------------------
  /                        '/'
----------------------------------------------------------------------
  ^                        the beginning of the string
----------------------------------------------------------------------
  v                        'v'
----------------------------------------------------------------------
  [0-9]                    any character of: '0' to '9'
----------------------------------------------------------------------
  [0-9]                    any character of: '0' to '9'
----------------------------------------------------------------------
  \.                       '.'
----------------------------------------------------------------------
  [0-9]                    any character of: '0' to '9'
----------------------------------------------------------------------
  [0-9]                    any character of: '0' to '9'
----------------------------------------------------------------------
  -                        '-'
----------------------------------------------------------------------
  [a-z]                    any character of: 'a' to 'z'
----------------------------------------------------------------------
  [0-9]                    any character of: '0' to '9'
----------------------------------------------------------------------
  [0-9]                    any character of: '0' to '9'
----------------------------------------------------------------------
  [0-9]                    any character of: '0' to '9'
----------------------------------------------------------------------
  /                        '/'
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------