1. A method of identifying one or more source units of translation in a block of source content, so as to segment the block of content into the one or more source units of translation, comprising: selecting one or more delineating characteristics of the source content in addition to lexical characteristics; determining instances of the delineating characteristics in the block of source content, and identifying one or more pairs of the instances within the text; for each pair of instances of the delineating characteristics, associating a first instance of the pair with a first boundary of a source unit of translation, and associating a second instance of the pair with a second boundary of the source unit of translation.