Is there a term for the use of a letter or numeral to substitute for a word or syllable in casual writing, such as "R U 4 real" in a text message?
My search returned the word rebus, defined as a puzzle in which words are represented by pictures and letters, but I don't think that "R U 4 real" is meant as a puzzle for the reader; rather, it's meant as a simple way to communicate informally. My other searches found terms such as acronym, grapheme, and leetspeak that don't seem to apply.
If there is a word for this substitution, does it apply both to intentional misspellings, such as "We 8 Bar-B-Q," and to unintentional misspellings, such as a restaurant menu listing the item "barbeque ribs"?