it's not a transaction until it goes onto the ledger. also, the id should function as a lot number, for instance, you have 3 one-dollar notes, and make three conditional-offers, each one of them should refer to one specific note (maybe even by serial number), to make sure funds are reserved while the conditional promise is outstanding. "asset id" is closer to serial number than "transaction id".
it's not a transaction until it goes onto the ledger. also, the id should function as a lot number, for instance, you have 3 one-dollar notes, and make three conditional-offers, each one of them should refer to one specific note (maybe even by serial number), to make sure funds are reserved while the conditional promise is outstanding. "asset id" is closer to serial number than "transaction id".