Amount fields apply to transaction-creation bodies, not every transaction endpoint. v1 creation payloads use decimal value; the API accepts a JSON number or string, although a string avoids client-side IEEE-754 rounding. v2 direct, hold, block, and unblock creation endpoints require string amount. Commit, cancel, and revert are ID-only lifecycle endpoints and have no amount request body.
Do not combine field conventions from different transaction versions. Use the API reference for the specific operation you call.
