Poster Abbreviations

OS	One Sheet (27" x 41" or 27" x 40" for recent releases) - This is the standard US poster size.
INS	Insert poster (14" x 36")
WC	Window Card (14" x 22")
HS	Half Sheet (22" x 28")
3S	Three Sheet (41" x 81")
LC	Lobby Card (11" x 14") Typically a scene from the movie with some of the film's logo or artwork.
TC	Title Card (11" x 14") Usually the first card in a Lobby Card Set which contains the film's logo and artwork.
BQ	British Quad (30" x 40") - This is the standard British poster size. The images are usually oriented in a landscape style as opposed to a portrait style for US posters.
LOBBY SET	Typically a full set of 8 Lobby Cards (11" x 14") although some sets may contain more or less.
PB	Pressbook. A booklet that contains poster artwork, articles, information, photos and other items used to advertise and promote the film.