Three days ago I was scanning Unicode (looking for useful characters for a roguelike, as one does), came across the metrical triseme (⏗), tetraseme (⏘) and pentraseme (⏙) in the Miscellaneous Symbols section, and added them to wikipedia. As far as I could ascertain, these are used to indicate scansion - https://en.wikipedia.org/wiki/Scansion#Other_symbols - which is apparently primarily a term used to describe rhythm and meter in a poetic context. However, the Expletive infixation page uses the alternate term prosody in perhaps more of a formal linguistic sense. PS: prosody & scansion. Certainly on the cryptic crossword one of these decades...