How to use AES correctly in BPS Format Preserving Encryption I have several questions on using AES 128bit in the BPS format preserving encryption

Which modes are acceptable?  (Should the block cipher used at each round be deterministic (ECB) or probabilistic (CBC, CTR etc)

What IV to set?  Can I set it to the constant zero?
AES is directly used as a block cipher without a mode of operation in BC / BPS. 

This would be identical to ECB mode for one block or CBC mode for one block and a zero IV in the case that the block cipher itself is not directly available. In that case you should not pad or remove a full block of padding if padding cannot be avoided. CTR of one block with a zero IV/nonce would also work.

But basically the answer to "what modes are acceptable" is: none. In that case the IV is also not applicable. The tweak can be seen as a specific kind of IV. Likewise you could see BC itself as a mode of operation for the block cipher.