[fukawi2]

My first job was supporting and developing order related systems for retail and wholesale (separate systems, but we operated both the wholesale and retail operations).

Wait until you start having to deal with Forward Orders, Back Orders, Special Orders, Cancelled Orders, and Refunds. Not to mention the General Ledger postings you have to make for each transaction too.

An "order" sounds super simple, but there are so many variations and corner cases.