Evidently obs term originally having to do with the weight of mdse though exact meanings are hard to pin down because it isn't found in many dictionaries. A quick googling suggests A later use, in reference to various forms of radiation, revealing connections to lasers, the sun, cameras, and stage lighting; but submerged in jargon that I can't fathom, eg:
Only High End Systems offersthe lighting professional a choice of zoom ranges....and 2:1 zoom fixtures for longerthrow or ~ applications where output is king and ultra wide zoomrange is not critical--www.tlsinc.com/pdfs/nlaprmay03.pdf
I was looking for an effects light for ~, gobo projection and those types of things, but the lack of fans in the VL1000 units was key for me--www.allstar-show.com/Epcor%20Centre_VL2500.htm
Twenty-something MAC 500s were scattered on the deck, on the upstage truss and a few on the downstage to provide ~, scans and effects lighting--www.totalproductionus.com/SiteFiles/oct_Dodd_Tech.htm
