break down and read an individually string
[I assume, since curving things can proceed clockwise or counterclockwise but straight ones can't, that you mean that it would draw the Line at an angle that is measured clockwise or counterclockwise by the specified number of degrees from 0, that is, @Anonymous>45 would be equivalent to @3<-45 or @3<315.]
If such a thing were always to be used inside the drawing of a single Line, I can imagine defining a command that would start the Line command, ask for a start point, ask for the input for the next point, which it would interpret as described, and end the Line there -- all self-contained in one command. If, however, you're looking for something that could be used for relative displacement under any circumstances [e.g. in a Move or Copy command, for the next vertex of a Polyline or the next end within a series of multiple sequential Lines, etc.], I think it would require you to be aware of the distinction between this and the standard way, and give it input that would be more different than merely reversing the angle bracket character, for instance as a function name in parentheses with a text-string argument, such as:
(MyAngle "@3>45")
or maybe:
(MyAngle)
without including the argument, and it would prompt the User for the special-format string.
That's because you can't enter something directly at the Command: prompt when it's asking for the next point if it's not in the format AutoCAD expects -- if it's going to need to be interpreted, I think it's going to need to be used inside a function that does the interpreting. Even if you built something to catch an error instead of merely kicking you out, it wouldn't be able to work with what you had typed in non-standard format unless that's saved as a variable, which would also require being inside a defined function.
Maybe someone else knows of a way to accomplish it, but I"m thinking it's likely that the usage of a solution would be more cumbersome than just typing in the minus sign when you want an angle measure clockwise: @3<-45. [Maybe you weren't aware that you can do that....]
