VS

VS is the format used for solid model files in Vellum Solids from Ashlar-Vellum, which later became Cobalt.

Software
A free viewer can be downloaded in the publisher's site, for Cobalt but will also view Vellum Solids files.

Links

 * Wikidata: Ashlar-Vellum
 * Upgrading from Vellum Solids