It is a primer applied to the edges of the plate in drywall systems to prevent dusting.
Gypsum plasterboard is a horizontally applied carrier profile which is applied vertically in Gypsum Board and Wall Cladding Systems.
Safeboard is a joint filler used in joints of gypsum board types.
In Gypsum Board Suspended Ceiling Systems; It is the profile used in floor and ceiling in walled wall cladding systems.