This concept is referred to as archival arrangement. It is usually a numeric system. XXX represents the record sub-group which is a further division of the record group. It is defined as smaller bodies of organizationally-related records. Associate Dean Associate Director, etc.
XX represents filing units.
Examples of thse include correspondence, personal papers, and employee manuals. The UCCS Archives includes administrative records and materials that document UCCS groups, activities, development or experiences. These can include but are not limited to correspondence, reports, committee minutes, agendas and publications. Central Administrative Records Recorded information that pertains to UCCS in part or in whole, that is issued by central administration. These can include but are not limited to reports and studies.