XML flies are gauges.
In the old days gauges were .gau files, still used on older panels on older models and sometimes on newer models too. In more recent times, on more recent models with more recent panels, they have been superseded by .xml files.
The visual components like instrument dials are separate bitmap files. Because the bitmaps can be opened and edited with any image program, and since the xml files can be opened and edited with Wordpad or Notepad, it's a simple matter to make alterations to the gauges. To edit the old .gau files you need dedicated software.
In the circumstance under discussion, if the clock is an xml gauge the required edit is probably simple. There is probably a line with a value that can be edited to make the clock show either 12-hour or 24-hour time. If it's a gau gauge it won't be so simple. But you could probably find an xml clock gauge to substitute. Or for that matter, a gau gauge that shows 24-hour time.
FS doesn't care which type of gauges the panel uses. Many panels have some old gau gauges and some newer xml ones.
