The domain which has been selected for OVIS (information dialogues concerning public transportation) and the fact that OVIS deals with spoken language, imply that it is crucial that a number of grammatical phenomena are described in a robust manner. In particular, temporal expressions, locative expressions (names of cities and stations), and a number of typical spoken language constructions, such as greetings, occur frequently in such dialogues.
The grammar rules and lexical entries for these phenomena make use of the OVIS2 grammar formalism, but are not organised according to the linguistic principles discussed above. This is true not only for the syntax, but also for semantics. The reason for dealing with these phenomena by means of a set of more or less ad hoc rules and lexical entries is that the constructions discussed below are often extremely idiosyncratic. At the same time, describing the regularities that can be observed does not seem to require the overhead of the grammar architecture we assume for the rest of the grammar. The most economical and robust solution seemed therefore to encapsulate the grammar for these constructions in relatively independent grammar modules.