This paper describes a generic lexicon tool which uses lexical representations and finite state transducers enhanced by arithmetic operations in DATR to generate individual output formats from a general phonological feature based representation. The tool was developed in connection with the lexicon component of a diagnostic evaluation toolkit, BEETLE, for a linguistic word recognition system. This lexicon is used online by the system to distinguish between actual and potential syllables and used offline for evaluation purposes with respect to a particular corpus. Rather than design a syllable lexicon which can only be used for these two tasks, it was decided to develop a more generic lexicon from which specific lexica can be generated on the fly; BEETLE is, therefore, only one application of the generic lexicon tool which can be used to generate output formats for other speech technology and multimodal applications.