Clue: They often require referrals: Abbr.

Answer: HMOS

Length: 4

---

Similar Clues:

• It may require a password: Abbr. (ACCT with 4 letters)
• Food vendor's requirement (abbr.) (LIC with 3 letters)
• TheyÂ’re within a certain range: Abbr. (MTNS with 4 letters)
• Required: Abbr. (NEC with 3 letters)
• Gift exchange requirement: Abbr. (RCPT with 4 letters)
• Reply requirement: abbr. (SASE with 4 letters)
• Check-cashing requirement: Abbr. (SIG with 3 letters)
• Uniform requirements: Abbr. (STDS with 4 letters)
• They'll route for you (abbr.) (AAA with 3 letters)
• Motel sign abbr. (e.g. AAA with 3 letters)