A flat surface on which outdoor advertisements are posted
Posting Platform/Catwalk- the valuation of the sign will require an 
adjustment .... B. Poster Panel-A structure that is designed to support a flat 
surface upon... [DOC] [TLE] 36 must-see examples of billboard advertising | Creative Bloq [PAR] May 12, 2016 ... And that's where billboard advertising comes into its own.