There used to be a page on your site with an icon reference. I used it all the time.
https://docs.mobiscroll.com/jquery/icons
Where has it gone?
Here you can find the docs for using external icons: https://docs.mobiscroll.com/5-25-1/icons - actually, the problem is that the Icons section is not yet migrated to the new docs and that’s the reason why you couldn’t find there.