Blockcast This document specifies how the Forward Error Correction (FEC) mechanism for Media over QUIC (MoQ) is used when protected tracks are delivered over multicast. It defines repair-only multicast endpoints and how a receiver adds and drops the repair layers they carry, states which tracks a multicast endpoint carries in this revision, specifies how a receiver treats blocks and symbols that a multicast content-authentication profile has not admitted, and specifies the receiver repair policy of a multicast or AMT leg: in-band FEC first, then per-block unicast repair for the blocks that FEC did not recover, with a budget and priorities derived from the catalog. It is independent of how multicast is carried, whether by Source- Specific Multicast and Automatic Multicast Tunneling or by a multicast QUIC channel.