Standard SLoc field in table T320

Dear gurus,

Please help me get some idea on following.

1. In Table T320, there is a field 'Standard storage location'. Please tell me where to set it in config and its use.

2. I have one warehouse with three storagelocations and while creating TR, user wants to key in only the Plant, material and qty. Storage location has to be automatically populated. (when Sloc is not entered, system throws an error "Plant/Storage location not defined"). Can i achieve this by setting X for the SLoc on the standard location field of the T320 table?. what will be the impact of setting one Sloc as 'standard Sloc' on other storage locations?

Thanks in advance!