1. A method of transforming an input sequence of unstructured speech recognition text into output structured document text, the method comprising: providing a probabilistic word substitution model to establish association probabilities indicative of target structured document text correlating with source unstructured speech recognition text; considering a set of candidate sequences of structured document text based on the word substitution model with respect to an input sequence of unstructured speech recognition text; evaluating the likelihood of candidates corresponding to the input sequence of unstructured speech recognition text; determining as an output a most likely sequence of structured document text.