the token and may include at least one of viewed written or spoken modalities moreover each modality type might be further defined e g the spoken modality might include different languages spoken by humans according to a geographic region in addition the distance metric could be calculated based on any number of techniques known to those skilled in the art for example when evaluating printed text the techniques described by belongie et al u201c matching shapes u201d eighth ieee international conference on computer vision july 2001 might be used see generally veltkamp et al u201c state of the art in shape matching u201d principles of visual information retrieval 2001 since calculating the distance metric could take a considerable amount of time on a processing device of computer system 110 an alternative embodiment of the present invention uses heuristic combinations to improve the efficiency of the present invention on the processing device a heuristic combination is a token distance metric pair that has been pre calculated and stored on a storage device preferably the heuristic combinations are stored in a persistent storage device e g a heuristic combinations table which has been indexed for efficient comparisons between the submitted token and the stored heuristic combinations thus when evaluating the submitted token in step 210 system 110 would compare the submitted token and portions thereof against the tokens stored in the heuristic combinations table and retrieve the distance metric upon a match the values stored in the heuristic combinations table according to one embodiment of the present invention may represent troublesome tokens that frequently appear in a particular modality type for example as previously mentioned the numeral one and the lower case letter l appear identical in some fonts consequently a token for the numeral one and a token for the lower.