Micros and Aloha are definitely the biggest two, and it makes the most sense to start there. But you also have to keep in mind that they both have multiple prod

Micros and Aloha are definitely the biggest two, and it makes the most sense to start there. But you also have to keep in mind that they both have multiple product lines (plus legacy systems), each with different capabilities and SDKs. The worst part is dealing across vendors though. The APIs are incredibly inconsistent between them, and some are frankly, crippled.