This report is the user's manual of SASS v.21, the Spreadsheet Anthropometric Scaling System (version 2.1). It describes the usage of SASS, a spreadsheet-like system which allows flexible interactive access to all anthropometric variables needed to size a computer-based human figure, described structurally by a PEABODY file. Data that may be accessed is organized into the following "groups": segment dimension ("girth"), joint limits, center of mass, and strength, all of which work based on statistical population data. SASS creates generic computer-based human figures based on this data. SASS also is an anthropometric database and interactive query system that works upon anthropometric data of real individuals. Scaled computer-based human figures created by SASS can be displayed directly, and interactively changed, within the Jack software.