You might capture the optional source together with the date in a first pass, and then, inside an compound existence test, s/// such source data as does exist to $data1 while using the else clause to insert "No source indicated" or whatever as the new value for data1.

Inelegant, and maybe not efficient, but sometimes 2 regexen are better than one.

In reply to Re: Default value for capture in regular expression by ww
in thread Default value for capture in regular expression by redhotpenguin

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