Lots of regex ops start with "(?". The most common of which is grouping ("(?:...)"): 
/ab|cd/

[download]
will match 
ab

[download]
and 
cd

[download]
while 
/a(?:b|c)d/

[download]
will match 
abd

[download]
and 
acd

[download]

perlre

In reply to Re: more info about regex updates by ikegami
in thread more info about regex updates by raybies

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