Use floating-point fields in database file access paths

The collating sequence for records in a keyed database file depends on the presence of the SIGNED, UNSIGNED, and ABSVAL keywords in data description specifications (DDS). For floating-point fields, the sign is the farthest-left bit, the exponent is next, and the significant is last.

The collating sequence with UNSIGNED specified is:

Positive real numbers—positive infinity
Negative real numbers—negative infinity

A floating-point key field with the SIGNED keyword specified, or defaulted to, in DDS has an algebraic numeric sequence. The collating sequence is negative infinity—real numbers—positive infinity.

A floating-point key field with the ABSVAL keyword specified in DDS has an absolute value numeric sequence.

The following floating-point collating sequences are observed:

Zero (positive or negative) collates in the same manner as any other positive/negative real number.
Negative zero collates before positive zero for SIGNED sequences.
Negative and positive zero collate the same for ABSVAL sequences.

You cannot use not-a-number (*NAN) values in key fields. If you attempt this, and a *NAN value is detected in a key field during file creation, the file is not created.