Compressibility and Expandability:
A computer algorithm may be used to compress or expand (itemize) the enumeration and chronology data contained in an 863 Basic Bibliographic Unit or 864 Supplementary Material l field. Compression or expansion capability is indicated by the value assigned to the first indicator position (Compressibility and expandability) of the 853 or 854 Captions and Pattern field . The 853/863 and 854/864 fields are linked by the number in subfield $8 (Link and sequence number) in each field.
The contents of an 865 Enumeration and Chronology field for an index may not be compressed or expanded by computer algorithm because an ambiguous holdings string could result. For example, the first twenty-four volumes of an index that cumulates every fifth volume could be either v. 1-24 or v. 1/5-24. In the second holdings string, the first cumulation is shown but nothing is known about subsequent cumulations. The second indicator position of field 855 (Captions and Patterns-- Indexes) is undefined.
The specific data element requirements for compression and expansion by computer algorithm are given in the Input Conventions area of the 853-855 Captions and Pattern - General Information section.
