FAR 52.212-1
Instructions to Offerors — Commercial Products and Services
What it says
The standard instructions governing commercial offers: how to submit, required content, late-offer rules, and the government's ability to award without discussions on initial offers.
Why it matters on DIBBS
"Award without discussions" is the operative phrase: on DIBBS, your first quote is usually your only quote. Submit your best price — there is rarely a negotiation round.