A Federal Supply Schedule, also known as a Multiple Award Schedule (MAS), is a listing of contractors that have been awarded a contract by GSA that can be used by all Federal agencies.

Effective April 1, 2003, Buildings and Building Materials/Industrial Services and Supplies for Federal Supply Class (FSC)54, Pre-Engineered/Pre-Fabricated Buildings and Structures are included in Schedule 056 under the following Special Item Numbers (SIN's):

SIN 361-10:	Prefabricated Structures including Accessories and Options
SIN 361-10A:	Pre-Assembled/Prefabricated Modular Buildings (metal, steel, aluminum, wood and fiberglass) and accessories/options, including, but not limited to, utility buildings.
SIN 361-10B:	In-Plant Offices, Pre-Fabricated Modular Wall/Partition Systems and Enclosures, Mezzanines and Wire Partitions including accessories and options.
SIN 361-30:	Ancillary services related to Pre-Engineered/Prefabricated Buildings and Structures including field assembly, training, consultation and design assistance.  Excludes "Construction" as defined by FAR 36.102
SIN 361-32:	Installation & Site Preparation services for Pre-Engineered / Prefabricated buildings and structures.

*Prefabricated Structures were, until recently, included in Schedule 539 ( Solutions and More) and before then they were included in Schedule 5411-B .