ViewSonic Thinclient Operating System (VTOS) was a rebadged license-free
version of the ThinLinX Operating System (TLXOS) that was preloaded onto
Pi v3s that ViewSonic sold under their own product name (SC-T25).

VTOS used a tms_client named vdm_client that could only talk to a rebadged
ViewSonic version of TMS known as VDM 3.0.

After our deal with ViewSonic expired, they abandoned VTOS in favour of
Stratodesk NoTouch.