So when is an Orthoscopic an Orthoscopic?

Only those that are called Abbe Orthoscopic can be considered the original Orthoscopic. But there are derivatives that might be called Orthoscopic and this is where I think that the problem begins.
Plus as Rolando stated, Orthoscopic has a meaning, Abbe Orthoscopic is an EP type.

Attached Image:

The word orthoscopic is an adjective with a specific meaning, and is not capitalized. An eyepiece free of rectilinear distortion - or perhaps with a minimum amount - would be called an orthoscopic eyepiece, with no implications of the specific design.

Astronomers seem to have changed orthoscopic to a noun, and often write it as "Orthoscopic," perhaps because many eyepiece designs are named after people, and should start with a capital letter. It is obvious that writing Orthoscopic is confusing, because there are many designs that are orthoscopic. Specifying the design, such as Abbe Orthoscopic, seems to nicely avoid confusion.

Now we should get back to that age old question about angels on the head of a pin.

Clear skies, Alan