CPLs (Composition Playlist) are key components of the cinema industry's content ecosystem. Stored inside DCPs (Digital Cinema Package) along with all the content, they are the instructions on how to build different versions of that same content. Without something like a CPL, every version of every film would need to be individually sent out in full, which would be completely impractical. Today's cinema software also relies on CPLs in order to select the correct version for playback.
The DCP itself can't hold any information on what different versions are included in it beyond the file name of the CPLs. Considering all the different variables that affect versions (2D/3D, languages, audio format, etc.), the CPL file name could quickly become too long, unwieldy, and jumbled to be useful. So a naming system was devised to make CPLs more readable to people, as well as standardised for the systems that rely on them for automations.
One of the first considerations that shaped the naming convention was technical- some screen servers were only capable of showing 40 characters. So, if the full content title was displayed in the CPL title, it wouldn't leave room to display anything else. To help cinemas identify their content, the format of CPL titles was standardised by studios and ISDCF(Inter-Society Digital Cinema Forum) into a "Digital Cinema Naming Convention". Its two main purposes are to keep as much information visible on screen as possible, and to specify the order and format of the information.
The resulting standard CPL file name is usually structured like this:
Title of DCP_Content type-Content modifiers_Aspect ratio_Language-Subtitle language_Territory-Rating_Audio type_Resolution_ Studio_ Date produced_Production facility_Version
Here is the CPL along with the formats that the versioning details would be in:
Note that if there is no entry for any of the fields, it will not be left blank, it will state NULL instead.
SMPTE DCP, the new standard
The cinema industry is in the process of transitioning to a new standard in DCP- the SMPTE DCP. It will add support for 'extended CPL metadata', which will allow some of the versioning data to be stored in metadata, instead of the CPL file name. This will allow the file names to become shorter and more readable, as well as enable systems like your TMS (Theatre Management System) to automatically select the right version for the right screen more reliably.
>Star Wars: Rogue One. Feature version 1. 2D. Scope. English audio with English subtitles. For USA. Rated PG-13. 5.1 audio. 2k resolution. Disney. Packaged on December 4th, 2016 at Deluxe Technicolor Burbank. Interop. Original version file.