How get coded data values in unimarc format via code

From: dasos ili <dasos_ili_at_nyob> Date: Thu, 16 May 2013 11:01:40 +0100 To: CODE4LIB_at_LISTSERV.ND.EDU

Greetings dear all, 

Let's say we have a file with many records in unimarc format, or Marc, it is almost the same.

could you please send me a hint on how get all coded data values for example for the fields 100, 101 102, for instance we would like to have the info: 100 appears 387 times, $a position character 8 length 1 appears 300 times, etc... you could use any language as an example. Thank you 