This document uses stream management terms described in [RFC9000], Section 1.3 including STOP_SENDING, RESET_STREAM, and FIN. It also uses RESET_STREAM_AT from [I-D.draft-ietf-quic-reliable-stream-reset]. RESET_STREAM_AT can be used by MOQT, but the protocol is also designed to work correctly when the extension is not used or not supported.
When this document says an endpoint "resets" a stream, it means the endpoint sends a RESET_STREAM or RESET_STREAM_AT frame on that stream (see Section 11.3.2 for considerations on choosing between them).