In a data decoder for decoding data from received symbols received over a channel from an encoder, a method for decoding data wherein the received data includes erasures and includes source symbols and repair symbols organized into one or more source blocks. The decoder uses a generator matrix, any square submatrix of which is invertible, such that the decoder performs decoding operations concurrently with the arrival of the source symbols and repair symbols that are a part of a source block. Novel methods for interleaving and specifying encoding structure for a large class of FEC codes, scheduling the sending of packets and the like, are also applied in conjunction with the method for decoding data.