According to the official help pages the following are required features in routing parts

Okay, cool. However when running our Elbows through the Routing Wizard I get this warning about the design table of them.

However 'Diameter@Route' and '\$PRP@Nominal Pipe Size' I was unable to find any mention of it in the help files.

What are they good for? Who knows? Are they 'required' ? And if so then why didn't we notice them missing the 10 years or so we've been using elbows without those 'required' paraemeters?

You might also notice that Diameter@Cpoint wasn't mentioned on the help page as being 'required' but it sure helps things going smoothly as we learned when it wasn't present. For that property there is a help page so that one can piece together that in fact it might not be required it is in fact pretty essential if you want the Routing add-in running smoothly.