Book Identifier codes are three letter codes used with a standard format text file to identify its book of the Bible. The first record of the file must follow this format: \id XXX. Where \id is the required SFM and XXX is replaced by the specific Book identifier code. All three letters of the code must be capitalized.
In general, the codes are the first three letters of the book name, but in some cases are changed when duplicates would occur. The following are examples of book identifier codes: MAT, 1CO, and 3JN. See Book Identifier Code table for a full list.