Page 31 of the Poser 11 PoserPython Manual - basically it's just the four most common operators, i.e. +, -, ×, ÷ (the latter either as divisor or dividend), plus a key/value pair option (which uses some sort of spline interpolation, with no option for linear) and a Python callback option (which appears to be spurious as a valueOp because simply setting up a callback via script does that job). I did google for alternative modulo algorithms, but none seem possible using valueOps, even the one you suggest - no 'floor' operator (the best result was this - 755.pdf (iacr.org))

It appears that writing a small Python callback is going to be the best way to do this.

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The 3Dcheapskate (also available in DAZ and HiveWire3D flavours) occasionally posts sensible stuff. Usually by accident.
And it usually uses Poser 11, with units set to inches. Except when it's using Poser 6 or PP2014, or when its units are set to PNU.