I posted the link to perlre and moritz posted the link to perlretut, which is where we both go looking for things that we don't remember. I suggest you do the same and follow these links and read the documentation.

#!/usr/bin/perl --
use YAPE::Regex::Explain;

die YAPE::Regex::Explain->new(
qr/[{},*]/ )->explain;

__END__

The regular expression:

(?-imsx:[{},*])

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):
----------------------------------------------------------------------
  [{},*]                   any character of: '{', '}', ',', '*'
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------
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