is merely that the "marker" in question is not a phoneme or sequence of phonemes but the element /Ø/. Along the way, it is hard to know when to stop positing zeros and whether to regard one zero as different from another. For example, if the zero not-marking can (as in he can) as "third person singular" is the same zero that not-marks deer as "plural", or if are both basically a single morphological placeholder. If it is determined that there is a zero on the end of deer in three deer, it is uncertain whether English adjectives agree with the number of the noun they modify, using the same zero affix. (Deictics do so: compare this deer, these deer.) In some theories of syntax it is useful to have an overt marker on a singular noun in a sentence such as My head hurts because the syntactic mechanism needs something explicit to generate the singular suffix on the verb. Thus, all English singular nouns may be marked with yet another zero. It seems possible to avoid all those issues by considering loss as a separate basic category of phonological change, and leave zero out of it. As stated above, one can regard loss as both a kind of conditioned merger (when only some expressions of a phoneme are lost) and a disappearance of a whole structure point. The former is much more common than the latter. In Latin are many consonant clusters that lose a member or two such as these: tostus "toasted, dried" < *torstos, multrum "milking stool" < *molktrom, scultus "carved" < *scolptos, cēna "dinner" < *kertsnā, lūna "moon" < *louwksnā ("lantern" or the like). Greek lost all stops from the end of a word (so *kʷit "what" > Greek ti, *deḱṃt "ten" > déka, *wanakt "O prince" > ána), but stops generally survive elsewhere. PIE *s drops medially between voiced sounds in Greek but is preserved in final position and in some consonant clusters. Old English [x] (voiceless velar fricative) is everywhere lost as such, but usually leaves traces behind (transphonologization). In furh "furrow" and mearh "marrow", it vocalizes. It is elided (with varying effects on the preceding vowel, such as lengthening) in night, knight, might, taught, naught, freight, fought, plow (Brit. plough, OE plōh), bought, through, though, slaughter; but /f/ in laugh, trough, tough, enough (and daughter can be found in The Pilgrim's Progress rhyming