1. A method of representing a sequence of symbol operations in a coding system, implemented as hardware or software, comprising: reading in instructions from an instruction store, wherein the instructions are selected from an instruction set and at least some of the instructions define operations on source symbols used to form output symbols; reading in source symbols from an source symbol store; executing the instructions on the source symbols using a processing unit to generate output symbols, wherein the instructions are independent of the source symbols and the processing unit configuration is independent of the particular instructions used, thereby allowing the processing unit to operate the coding system for different FEC (forward error correction) codes by changing the instructions and not changing the processing unit.