Subject matter expert; acronym pronounced either by spelling out (S-M-E) or as “Smee” (like Captain Hook’s sidekick). Lovely example of internally redundant terminology: What is an expert expert in, if not some subject matter? Likely driven by perverse need to use three-letter acronyms for perfectly ordinary concepts, but that’s another …
Technically not a problem in Proposal Land, since it happens after contract award, but good to be aware of the tendency when making commitments you’ll be held to later.
Leaving aside marine uses of this acronym (Sea Date Required to Load), a SDRL is a Data/Document Requirements List for a Supplier, Subcontract, or Subcontractor. Pretty much all the same thing: data deliverables under a contract. See also Contract Data Requirements List.