What's a specifier?

Nik and I were discussing my dissertation topic, and part of it related to the syntactic function that CGEL calls determiner, and which I'm calling specifier. Nik said he didn't really know what a specifier was. I don't think he meant in modern English in particular, where CGEL gives a fairly explicit list of characteristics. Instead, I think he meant more generally. For example, if you wanted to know if there was a specifier function Old English or in Dinka, or whatever, how would you know?

Subjects as specifiers

While reading Syntactic Theory by Sag, Waslow, & Bender, I once again ran across the idea (mentioned previously here), that the subject of a clauses (where Clause = Subj + VP) is analogous to the Specifier^† of an NP (where NP = Specifier + NOM). Here, however, the example given in (34) on p. 64 is unambiguously comparing a clause with an NP:

1. We created a monster
2. our creation of a monster

They use this idea in their constraints-based grammar to reduce the number of rules needed. Thus instead of defining NP one way and Clause another (they use S, but I'll stick with Clause), they can use one feature specification to capture both as in figure 1^‡:

Figure 1. A feature structure representing either Clause or NP.

(At this point, things get very technical.)

Were they al demonyak?†

In "The lady was al demonyak: historical aspects of Adverb all", Buchstaller and Traugott (B&T) consider the "development of the functions and structural properties of Adverb all, and suggest that degree modifiers in general should be analyzed in similar terms" (p. 345). They claim that the authors of CGEL mention "Adverb all as a ‘modifier in an AdvP’ that means ‘completely’, but do not subclassify it in their discussion of types of adverbs" (p. 345). The reason that all is not subclassified as a type of adverb is that it's not an adverb at all. It's a determinative.