For each AS/400 logical/physical, you can define a sorting sequence (diffrent from the current sorting sequence).
Check the QSRTSEQ system value to see what your system’s default value is. You also can check your job attributes (with option 2 of dspjob). The default system's value is *HEX.
To provide a case insensitive key search, you can create a logical file with ALTSEQ option, giving a file like QSYS/QSYSTRNTBL. Use ‘go CMDTBL’ to display, create or modify the tables.