Paraphrased from Avaya documentation: AUXIN is when the agent receives an inbound extension call [not an ACD call] while they are in AUX or Available, or while the agent has an ACD, AUXIN, or AUXOUT call on hold.
So, basically it's any call to their agent ID or the extension they logged onto that they answer and is not a call that queued to a split and routed to them as an ACD call.
Look on support.avaya.com for the Avaya CMS Management System Database Items and Calculations document to help with these data items. Release 14 is document number 07-601591
- Stinney
Quoting only proves you know how to cut and paste.