See OCLC Bibliographic Formats and Standards or MARC 21 for guidance. In OCLC this field is mandatory, in MARC it is optional. General guidelines 9.0B1. Chief source of information - Chief source of information for computer files is the title screen. Internal sources are preferred, but seldom used.
Most catalogers use the disc label.
Prescribed sources of information. Any source Publication, distribution, etc. Any source Series Chief source of information, the carrier or its labels, information issued by the publisher, creator, etc. Any source Standard number and terms of Any source availability Choice of entry - Because the responsibility for electronic resources is usually diffuse, they are usually entered under title. Often have unusual spelling or capitalization, and often have words that run together.