RRR is referring to Mopar's '@.050" ' duration conversion, referenced in the catalogs, take a 284°/.484" cam & multiply the 284×.850...=241.4°@.050" tappet lift.
They also clearly state to NOT use the calculated @.050" to select Your camshaft.
Interesting. I haven't heard of this. Wonder why they didn't just measure the @ .050" specs? Unless this comes from a time back before it was common to do so. Maybe this was used as a way to compare data from old catalogs or something?
It seems odd to provide a formula to calculate the @ .050" specs and then state "do not use". Unless all cams were ground with the same profile from seat to @ .050" ...
Nevermind, looking at it from todays perspective the whole idea seems short sighted but I kind of get why they may have done this.