The core of an ACIP file name is a 4-digit number, either from the Tohoku catalog or, where not in this catalog, the ACIP catalog number. Since Tohoku numbers for the Kangyur and Tengyur Collections go from 1 to 4569, these numbers can never be confused with a Tohoku Sungbum work, and so ACIP will also be using these numbers for other collections. For example, there will be separate works under K0001, S0001, and R0001, even though only the first refers to a Tohoku number. Thus the initial letter indicates the primary collection in which a work is found. After these one or two letters come the four digits of the core catalog number.
Numbers indicate multiple volumes, or sections of a very large work.
This is how a text is called up in the AsiaView program. The title of the text appears in a menu list, followed by its catalog number in parentheses. This catalog number is distinguished from the full file name in that it only identifies the text, and does not give additional information as to verification level, edition version, language, and so on. The catalog number of a text will not change over the years, but the file name may change, as the text moves up in verification levels.