> In summary, (proper) "time" is a parameter, not a dimension.

Do differences in proper time means ending up in a 
different 3d frame, with different t coordinate ?

> The Einstein quote seems to mean that "time" was dimension, but that
> SR's (proper) "time" was a new creature.

It is terribly difficult to convey it, since 
'time' is not real. It is derived from motion, and 
one way to control motion is inertia, and that is 
confused with proper time. This is the right 
terminology, but then nobody understands.

There is no proper usage for proper time.
It is not proper and it is not time.

Hayek.