Control field values for nonspanned key-sequenced, entry-sequenced, and variable-length relative record data sets

In a key-sequenced, entry-sequenced data set, or variable-length RRDS with nonspanned records, the possible hexadecimal values in the control field of an RDF follow.

Left RDF	Right RDF	Description
	X'00'	The RDF at X'00' gives the length of a single nonspanned record.
X'08'	X'40'	The right RDF gives the length of each of two or more consecutive nonspanned records of the same length. The left RDF gives the number of consecutive nonspanned records of the same length.

Figure 1 shows the contents of the CIDF and RDFs of a 512-byte control interval containing nonspanned records of different lengths.

Figure 1. Format of Control Information for Nonspanned Records

The four RDFs and the CIDF comprise 16 bytes of control information as follows:

RDF4 describes the fifth record.
RDF3 describes the fourth record.
RDF2 and RDF1 describe the first three records.
The first 2-byte field in the CIDF gives the total length of the five records-8a, which is the displacement from the beginning of the control interval to the free space.
The second 2-byte field gives the length of the free space, which is the length of the control interval minus the total length of the records and the control information-512 minus 8a minus 16, or 496 minus 8a.