In defining the labels for units, the distinction between form and function is an important one. In syntactic annotation of corpora, the level of analysis to which we devote most attention in this document relates to form rather than function. Function can be seen to be a further level of analysis, in which different categories may be shown to fulfill the same syntactic function within a large syntactic unit, e.g. a Noun Phrase may function as an Adverbial adjunct within a sentence, as may also a Prepositional Phrase or an Adverb. This problem compares directly with the issue in morphosyntactic annotation, in which the function of a word may be different from the morphosyntactic class of the word itself. Thus a noun may function as a modifier of another noun (fulfilling an `adjectival function'), e.g. colour in colour television, or a past participle form of a verb may function as an adjective, e.g. disputed in disputed territory. As a general rule, it is common practice to annotate firstly at a form level, and at a functional level optionally afterwards. This can be seen as advantageous since the initial level of annotation is one which provides basic descriptive information about the language (correlating directly with the type of information included in a lexicon of the language), the further annotation at a functional level would provide a richer, deeper analysis.