If you specify SZERO, MFX will treat numeric decimal (for example, SFF/UFF/ASF/AUF) of -0 and +0 as different values. This affects both collating (SORT/MERGE) and other operations like INCLUDE/OMIT.
If you specify NOSZERO, MFX will treat numeric decimal -0 and +0 to have the same value as +0. The delivered default is NOSZERO.