Default: True
Range: True or False

This parameter determines whether or not the program should request the NULL VALUES for data set records from the DBEngine during the define and redefine commands. The NULL VALUES are then stored in a binary file (datasource_NullRec.dat) from which they are retrieved at the beginning of a process or a clone command. When this parameter is enabled, the testing for NULL is more accurate; however, this feature generates a small amount of overhead, particularly with a large database where these records use more memory. Note that this parameter does not imply that NULLS are allowed in the relational database; this is still specified using the allow_nulls parameter.