A method and apparatus are described for specifying arbitrary words in a rule-based grammar, such as a context-free grammar. A wildcard identifier is used in a context-free grammar file in place of a predefined category of words. Artificial phoneme combinations that represent generic words in a speech...http://www.google.de/patents/US7302381?utm_source=gb-gplus-sharePatent US7302381 - Specifying arbitrary words in rule-based grammars
