You can see in Product search WebClient UI that a lot of search parameters are supported. They are displayed via drop down list:
Below is the logic about how is search parameter dropdown list in UI is determined:
(1) Starting point: controller->get_possible_fields
(2) The available fields come from DDIC structure which is defined in BOL Model browser and shared with all 5 product types
(3) All 40 fields act as “Available fields” in configuration. But in the UI, only a subset of them are visible:
