365 or 360 days... CFAI uses which for Derivatives?

So Schweser videos told me to use 365 days in the exponent (i.e. 90/365) to discount a cashflow for Forwards (let’s say Present Value of Dividends). I just did the CFAI Mock 2011 and the answer key for an equity forward question was with 360 days. Funny thing is if you used 365 you were exactly on another answer. I got it wrong. I’m pissed. Is there a statement on the conventions somewhere of what CFAI uses? Thanks! J