Some sources consider coalporters as gondolas. It can be argued that these high-side cars are actually open-bay hoppers. So, which categorization is correct for coalporters, particularly the bathtub Bethgons and 5-bay RD4s with rotary-couplers?
The only way to empty a Bethgon Coalporter is out the top, that makes it a gondola. The RD4 is a Rapid-discharge Hopper, even if equipped with a rotary coupler, since the coal can be unloaded through the hopper gates on the bottom.
I have it on good authority that the only time Coal Porter had anything to do with gondolas was when he was writing the musical Kiss Me Kate. [(-D]