565 Subfield $a - Number of cases/variables:

Subfield $a contains the number of cases or the number of variables in a single case within a repetitive case file series.

Example:

565 ##$3Military petitioners files$a11;$bname;$baddress;$bdate of birth;$bplace of birth;$bdate of application;$bdates of service;$bbranch of service;$brank;$bdate of induction;$blatest occupation;$bdependents;$cpensioners;$dCivil War (1861-65) veterans