Character position definition and scope:

These four character positions are undefined for Computer files.  They contain blanks or fill characters.

Record requirements for National-level and Minimal-level records:  Optional.

Content designator history:

As of 1995, the following definitions of these character positions were made obsolete:

008/18  Frequency

008/19  Regularity

See also:

006 and 008:  Computer Files

006 and 008:  Cross Reference Tables by Type of Material

006/01-17:  Character Positions by Type of Material

006  Fixed-Length Data Elements - Additional Material Characteristics

008/00-39:  Character Positions by Type of Material

008  Fixed-Length Data Elements