Formal notation A statement of the form A > B is to be read, "Sound A changes into (or is replaced by, is reflected as, etc) sound B". Therefore, A belongs to an older stage of the language in question, and B belongs to a more recent stage. The symbol ">" can be reversed, B < A, which also means that the (more recent) B derives from the (older) A": POc. *t > Rot. f means that "Proto-Oceanic (POc.) *t is reflected as in the Rotuman (Rot.)". The two sides of such a statement indicate only the start and the end of the change, but additional intermediate stages may have occurred. The example above is actually a compressed account of a sequence of changes: * first changed to (like the initial consonant of English thin), which has since yielded and can be represented more fully: t > > f Unless a change operates unconditionally (in all environments), the context in which it applies must be specified: A > B /X__Y = "A changes to B when it is preceded by X and followed by Y." For example: It. b > v /[vowel]__[vowel], which can be simplified to just It. b > v /V__V (in which the V stands for any vowel) = "Intervocalic [b] (inherited from Latin) became [v] in Italian" (such as in caballum, dēbet > cavallo 'horse', deve 'owe (3rd pers. sing.)' Here is a second example: PIr. [−cont][−voi] > [+cont]/__[C][+cont] = "A preconsonantal voiceless non-continuant (voiceless stop) changed into corresponding a voiceless continuant (fricative) in Proto-Iranian (PIr.)" when it was immediately followed by a continuant consonant (a resonant or a fricative): Proto-Indo-Iranian *pra 'forth' > Avestan fra; *trayas "three" (masc. nom. pl.)> Av. θrayō; *čatwāras "four" (masc. nom. pl.) > Av. čaθwārō; *pśaws "of a cow" (nom. *paśu) > Av. fšāoš (nom. pasu). Note that the fricativization did not occur before stops and so *sapta "seven" > Av. hapta. (However, in the variety of Iranian that led to Old Persian, fricativization occurred in all clusters: Old Persian hafta "seven".) The symbol "#" stands for a word boundary (initial or final) and so the notation "/__#" means "word-finally", and "/#__" means "word-initially": Gk. [stop] > ∅ /__# = "Word-final stops were deleted in Greek (Gk.)". That can be simplified to Gk. P > ∅ / __# in which P stands for any plosive. Terms for changes in pronunciation