uchar­classes – Font ac­tions in X∃TeX ac­cord­ing to what is be­ing pro­cessed

The pack­age takes care of switch­ing fonts when you switch from one Uni­code block to an­other in the text of a doc­u­ment. This way, you can write a doc­u­ment with no ex­plicit font se­lec­tion, but a se­ries of rules of the form “when en­ter­ing block …, switch font to use …”.