It apears to be a command in R5 ... http://docs.mcneel.com/rhino/5/help/en-us/commands/applywatermark.htm explains the process but does not provide any API library structure, and the same applies for their wiki http://wiki.mcneel.com/rhino/rhinov5status_watermarks, I have sent an e-mail requesting more information but will wait n see what comes back. I have a feeling that we may well find that this is just something unique to R5 and for obvious reasons would not be made public through their development kit as it would kind of compromise things i would think.

As always thanks for the speedy reply

Martin Spencer-Ford