This is probably (well, certainly - probably) kicking in an open door, but a good book on stuff like this is our very own davorg's Data Munging with Perl. Among other things, it discusses the care and feeding of pack and unpack.

CU
Robartes-

In reply to Re: data extraction from badly formated txt files by robartes
in thread data extraction from badly formated txt files by Anonymous Monk

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