A couple of days ago I bought seven VS1000 audio modules and already made some changes to the firmware. It works very, very well

I am very interested in being able to play the files by number and not by name, and at the same time use the GAPLESS option. All in order to simplify the command by the uart. How are names and numbers related, in alphabetical order, by the modification date or in some other way?
Thanks in advance,
Juan