Assign vendor number

I'm working on a 4GL program to enter AP vendors into a database and I'm wondering how the vendor numbers should be assigned. Should they be assigned sequentially or should they be assigned so that when selecting the data and ordering by vendor number the vendor name would be in alphabetical order? An old 4GL program we have does it this way, but I don't see any reason to do that. Does anyone have any reason why I wouldn't want to just assign the vendor number sequentially?