Had my Nexus renewal interview this weekend so asked about the ABTC while I was there (have had the conditional approval for over a year). This was on the Canadian side at YYZ.

First officer didn't know what to do, asked some others who said you just click a checkbox. A 4th agent overheard and walked over, saying no you need to show "documentation". I asked what's needed - she answered she'd only seen one prior applicant before and he came with "a stack of papers" including an employee letter explaining the need for ABTC membership, proving Asia business ties, etc. Of course that's not mentioned anywhere on the website (AFAIK??) but she was sure that that's what i need. Insisted that I come back when I have those docs so I said ok. The APEC card was an afterthought so of course I didn't "prepare" for it in any way.

Web status still shows conditional approval, not denied or anything. So I guess I'll try again next time.