This variable is for use only on VMS systems. When it is set to "1" (on,
true, yes), it causes the runtime to specify a key type for numeric keys. In order
to make use of this variable, you must also create XFD files at compile-time
("-Fx"), and you must set the configuration variable XFD_DIRECTORY to point to
the directory containing those XFD files.
When these steps have been taken, the runtime will create RMS files with keys
having either the packed decimal or integer attribute, under certain conditions
dictated by the RMS file system. In particular, a key will have the packed
decimal or integer attribute only if it is a single-segment key and only if there
is a single field in the key. In this case, a USAGE COMP-3 data item in the
key will receive the packed decimal attribute, and a USAGE COMP-5 data item (if
it is 2, 4, or 8 bytes long) will receive the integer attribute.
One effect of having this attribute set on key fields is that the order of the
data is changed. Without this attribute, a file that has records with keys
-3, -2, -1, 0, 1, 2, 3 would have those records ordered in this way: 0, 1, -1, 2,
-2, 3, -3. With this attribute, those records would be ordered in this way:
-3, -2, -1, 0, 1, 2, 3. The default setting for this variable is "0" (off,
false, no).