Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Compiler Description Language, or CDL, is a Computer language based on affix grammars. It is very similar to Backus-Naur form(BNF) notation. It was designed for the development of compilers. It is very limited in its capabilities and control flow; and intentionally so. The benefits of these limitations are twofold. On the one hand they make possible the sophisticated data and control flow analysis used by the CDL2 optimizers resulting in extremely efficient code. The other benefit is that they foster a highly verbose naming convention. This in turn leads to programs that are to a great extent self-documenting. The language looks a bit like Prolog (this is not surprising since both languages arose at about the same time out of work on Affix grammars). As opposed to Prolog however, control flow in CDL is deterministically based on success/failure i.e., no other alternatives are tried when the current one fails. This idea is also used in Parsing Expression Grammars.