Some Problems with Accents in TEX: Letters with Multiple Accents and Accents Varying for Uppercase/Lowercase Letters

The problems of using the internal command \accent as a tool for support of some Cyrillic writing systems is investigated. It is shown that the internal features of \accent prevent construction of some Cyrillic letters which require several accents simultaneously. A special macro which emulates the work of \accent by some other commands is suggested. The accents for I/i and J/j, which are different for uppercase and lowercase letters, are also considered. If-then-else structures by use of which correct accents can be placed, depending on the letter case, are proposed. A similar technique can be used for case change of the Cyrillic “capital form” ligatures and .