Abstract: Non-deterministic text with average word recognition precision below 50% is processed utilizing non-textual differences between words or sequences of words in the text to provide more useful information to users by resolving more than two decision options. One or more indexes that indicate non-textual differences between n-word sequences, where n is a positive integer, may be generated for use in data mining that considers the non-textual differences. Alternatively, multiple indexes may be generated using different data mining techniques that may or may not utilize non-textual differences and then the results produced by the different data mining techniques may be merged to identify non-textual differences. These techniques may be used in classifying, labeling, categorizing, filtering, clustering, or retrieving documents, or in discovering salient terms in a set of documents.