I believe those are the _EX1 versions of the increase/decrease events that are bound in the menu. For maximum compatibility (because hardware and addons can use any of the events), you should intercept all throttle events eventually.
In the case of the Caravan, the ASOBO_ENGINE_Throttle_SubTemplate template is used so throttle increase goes through the ENGINE_Throttle_1_Inc input event (Engine_Inputs.xml).
This input event uses the THROTTLE1_SET key event.
As Matt mentioned, this really depends on implementation so you probably want to intercept all of them.