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Reference-frequency generation for optical fiber instrumentation is now restricted to the frequency bands in which the reference materials have well-resolved absorption lines. We study analytically and experimentally the possibility of generating reference wavelengths by use of Raman-enhanced four-photon mixing in an optical fiber. We show that it is possible to generate efficiently frequencies that are 10–40 nm away from the absorption bands of the usual reference materials: acetylene (^12C_2H_2), hydrogen cyanide (HCN), and similar or derived species. As a demonstration we use an acetylene cell to generate reference frequencies that cover the whole C (1530–1565 nm) and some part of the L (1565–1625 nm) transmission bands of the optical fiber.