The KeyMap class is used to store a set of values with associated keys which identify the values. The keys are strings. These may be case sensitive or insensitive as selected by the KeyCase attribute, and trailing spaces are ignored. The value associated with a key can be integer (signed 4 and 2 byte, or unsigned 1 byte), floating point (single or double precision), character string or AST Object pointer. Each value can be a scalar or a one-dimensional vector. A KeyMap is conceptually similar to a Mapping in that a KeyMap transforms an input into an output - the input is the key, and the output is the value associated with the key. However, this is only a conceptual similarity, and it should be noted that the KeyMap class inherits from the Object class rather than the Mapping class. The methods of the Mapping class cannot be used with a KeyMap.
A null Object pointer (AST__NULL) will be returned if this function is invoked with STATUS set to an error value, or if it should fail for any reason.