Technical writing is governed by a variety of well-established guidelines and standards. Some standards, such as IEEE Std 260.1-1993, Letter symbols for units of measurement, focus on a single topic. Others, such as the Chicago Manual of Style and the Microsoft Manual of Style for Technical Publications, offer guidance on the gamut of publication preparation. Simplified Technical English (simply referred to as STE), comprises a complete set of writing rules and a lexicon of approved and unapproved words designed to support authors in the creation of unambiguous and understandable text.