I cannot find information on how to identify fittings (ducting or piping) for a Lookup Table when there are 2 pieces of information needed to define the part. For example: a wye fitting has 3 connections which can all be the same size or have a branch smaller than the barrel of the fitting. No problem calling for a 4" wye but how do you call for a 4x3 wye or a 4x2 wye using a lookup table? Do i have to generate a couple of "Dummy" parameters?