This study employs a knowledge intensive corpus analysis to identify the elements of the communicative context which can be used to determine the appropriate lexical and grammatical form of instructional texts. IMAGENE, an instructional text generation system based on this analysis: is presented, particularly with reference to its expression of precondition relations. INTRODUCTION Technical writers routinely employ a range of forms of expression for precondition expressions in instructional text. These forms are not randomly chosen from a pool of forms that say "basically the same thing" but are rather systematicaUy used based on elements of the communicative context. .
