565 Subfield $b - Name of variable:

Subfield $b contains the name of a variable in the file. Subfield $b is repeated for each variable name listed.

Example:

565 0#$bService satisfaction survey$a5;$bcounty of residence;$bage;$beducation level;$bdate of request;$bsubject area of request;$dperformance files Sept. 1983 through June 1984;$cmedia center users