One of my clients has an AA corporate discount-- a massive percentage off F/A/J/D/Y (but not discounted Y) fares. However, it does not apply to RTW fares or Oneworld partners. So, for ORD-Asia travel, it's always routed through NRT and onto JL codeshares (vs. CX via HKG). Codeshares are only included when it's part of a connection off AA trans-Atlantic/Pacific.