The SOW typically also includes detailed requirements and pricing, with standard regulatory and governance terms and conditions.
Many formats and styles of statement of work document templates have been specialized for the hardware or software solutions described in the request for proposal.
Many companies create their own customized version of SOWs that are specialized or generalized to accommodate typical requests and proposals they receive.
SOWs are typically replete with "contractor shall" statements of mandatory compliance (for example, "This task shall be performed in accordance with Agency xyz Directive, dated mm/dd/yyyy").
Aside from good practice, there is little government policy guidance that emphatically prescribes how and when to use SOWs versus SOOs or PWSs.
SOWs are usually contained in the government's solicitation (RFP or RFQ) and carried forward, as may be negotiated with the offeror, into the final contract.