It is important to remember in a study like this one, which looks primarily at
cross-dialectical communication, that any account of a language-system like
English is extremely idealized and abstract and inevitably based on the
standard form of the language (a form routinely used, it should be noted, by
only a small minority of speakers). Although the notion of a standard is
notoriously complicated and hard to pin down, it is useful here to ignore the
social dimensions of standardization and adopt Lyons' view of it as one kind
of idealization of the data in which the linguist ignores differences within a
system and Hdiscounts all but the major systematic.variations in the language
behaviour of the community" (Lyons, 1977, p. 587). Standard English then
is the form of the language from which most linguists cite their examples,
and it is usually believed that structural differences between standard and
non-standard varieties are relatively superficial and can be accounted for in
terms of rule addition or rule loss. Some examples of syntactic differences
within British English are cited by Hughes and Trudgill (1979) which include
differences in tense and aspectual systems, and in the formal distribution of
individual verbs such as have and do.