American Express Membership Rewards - MR points to miles -- odd lots?

I know that the minimum transfer is 1000 points. But do I have to transfer in increments of 1000 or can I transfer in odd lots to top off my account exactly? (For example 1541 MR points to 1541 Delta miles).

I'm interested in the general policy, but if it varies by airline I'm specfically interested in Delta.

Thanks.

Membership Rewards
Points to be transfered
Delta Air Lines
Delta SkyMiles®

Enter the points to transfer
in increments of 1,000

MR points to hotels and airlines are always in even increments, you can't do odd lots.