apostrophe) forms adverbs of time: nowadays, closed Sundays. There is a literary periphrastic form using of, as in of a summer day. There are also forms in -ce, from genitives of number and place: once, twice, thrice; whence, hence, thence. There is also the "genitive of measure": forms such as "a five-mile journey" and "a ten-foot pole" use what is actually a remnant of the Old English genitive plural which, ending in /a/, had neither the final /s/ nor underwent the foot/feet vowel mutation of the nominative plural. In essence, the underlying forms are "a five of miles (O.E. gen. pl. mīla) journey" and "a ten of feet (O.E. gen. pl. fōta) pole". Status of the possessive as a grammatical case Historically, the possessive morpheme represented by s was a case marker, as noted in the previous section, and the modern English possessive can also be analysed as a grammatical case, called the "possessive case" or "genitive case". However, it differs from the noun inflection of languages such as German, in that in phrases like the king of England's horse the ending is separated from the head noun (king) and attaches to the last word of the phrase. To account for this, the possessive can be analysed, for instance as a clitic construction (an "enclitic postposition") or as an inflection of the last word of a phrase ("edge inflection"). (The form the king's horse of England was the correct form in old times, but not now.) For instance, The Oxford English Grammar, under the heading "Case", states "In speech the genitive is signalled in singular nouns by an inflection that has the same pronunciation variants as for plural nouns in the common case." A Comprehensive Grammar of the English Language, under the heading "The forms of the genitive inflection", similarly refers to the "genitive inflection with regular and irregular plurals", but later – especially with regard to the "group genitive" – revises this to clarify that the -s ending is not a case ending as in German or Latin but is "more appropriately described as an enclitic postposition". The Cambridge Grammar of the English Language discusses the possessive in greater detail, taking account of group (or phrasal) genitives like the King of England's and somebody else's and analyses the construction as an inflection of the final word of the phrase (as opposed to the head word). The discussion in support