Is there a source that explains these codes?

Page 28 of 50 in the manual describes typical posted info in the code.  I'll update to clarify that
 R is the tool tip radius and IC is the Inscribed circle of the tool.

If there is ever a reason to update the LazyTurn manual, I'm available to assist.

Thanks for the offering, but don't envision much updating other than what makes sense from user replies.

I’d like to overcome the quirks in LC

It is what it is and there will be no additional development that I know of.

it doesn’t work all the time

Frankly never use offsets much here and as said, it functionality was never tested to any great extent.
Remember WYSIWYG....

RICH