[EricH]

I can't find anything saying that it's an official rule. However, it is reasonable for it to be a guideline to make it easier for the refs. If you aren't sure, Q&A. Now. This is something that could bite teams during Week 1. It will affect play, at least for a bit. Right now, it's not enforceable by the rules. Either the rules have to change (1 update chance to do that) or the requirement must leave.