OK, so what the standard seems to require is that the
cord manufacturer indicate that the cord compression fitting is suitable for use with the cord.
The UL listing for Cord Sets and Power-Supply Cords (ELBZ) has no reference to fittings used to clamp the cord at the appliance. See 2013 White Book available for download from UL.ORG.
In the dim, dark past, when rats wore clothes, the use of SO like cable was recognized as a fixed wiring method for wet or damp locations, dairys, cold-storage warehouses .... As far as I can recall the fittings used were gland using a "rubber" interior fitting around the cable and a external nut/cup used to compress the rubber. Such fittings are still sold.
Once again unless this is a 3-phase or a (250V?) current greater than 16A, the best solution is a C13/C14 (10A) or C19/C20 (16A) cord and chassis connector. The connectors (male chassis mount) and the cord can be easily gotten with a dozen or so European/Worldwide standards compliances.
see:
http://en.wikipedia.org/wiki/IEC_60320 for an English summary on these.
If you require more current or 3-phase, then you need to find a US or other vendor who will designate a cord clamp that is suitable.