Examples are EU [i: ju:], IBM [ai bi: em], ALT [ei el ti:] (though the latter is also sometimes taken as an acronym and pronounced [o:lt]).
Most first-letter abbreviations in English and other languages using the Latin script are alphabetisms. In Hebrew and Arabic, alphabetisms do not exist at all, and they obviously do not exist in languages with non-alphabetic writing systems.
Sometimes alphabetisms are not distinguished from acronyms and are simply called "acronyms".
- German Alphabetismus