1) ROTC relative 
opportunities to see. The aggregated published or acknowledged readership numbers for all content in which a brand or organisation receives earned content. See also eyeballs and impressions.)
abbreviation: Organized Track System
On The Scene -or- On The Spot -or- Off The Shelf
over the shoulder
Is the Office of Thrift Supervision. 
Organized Track System
acronym: Office of Toxic Substances (EPA)
Office of the Third Sector
Officers' Training School.