Deadline for "pre-draft" trades of draft picks

[DBoys]

Once the NBA draft begins - teams can't trade picks, but instead they agree to trade and then pick for each other. And the NBA doesn't allow "last second" trades before the draft begins, to sidestep that weird result. So I'm wondering, does anyone have a reference to some place authoritative that defines exactly when the cutoff is for a pre-draft trade of a draft pick, that allows each team to be re-slotted?

For example, I believe that last year the Sixers picked 1st and were announced as picking 1st, with the Celtics picking 3rd. So they would have done their trade before whatever deadline.

My belief is that it's the close of NBA business day the day before. But I can't find anything in the CBA that actually defines it that way. Or a different way, for that matter.

Does anyone know for certain, with reference to the document wording on which it's based?

Thanks.

[Hopper15]

When the trade deadline has passed. Teams are free to make trades again once their season has ended, but cannot trade players whose contracts are ending or could end due to an option or ETO.

[DBoys]

Thanks but that really doesn't address my question in any way at all.

[Smitty731]

I believe it's in the Operations Manual vs the CBA. Last year I know for sure the deadline was 3 PM EST, because that was widely reported.

[DBoys]

I believe it's in the Operations Manual vs the CBA. Last year I know for sure the deadline was 3 PM EST, because that was widely reported.

Thank you.