Posted by Gary S on Jul 29, 2022; 11:10pm
URL: https://forum.librecad.org/Alternate-for-relative-coordinates-tp5721933p5721945.html

"Apparently the first entry becomes the new relative point for the second." - Correct.

"The only way I understand I can do this is to make a reactangle elsewhere and then move it into place." - No, you shouldn't have to do that.  Place your first point of the rectangle with an "absolute coordinate".  Say you want it to start at 10, 20 and then have a rectangle 30 wide and 15 tall.  To specify the first corner type "10,20".  For the second corner you would type "30..15" (which is equivalent to @30,15):
   re
   10,20
   @30,15

The next prompt of the "Command line" output is then "Specify first corner" again for another rectangle.  Coordinates always need to be entered as a "x,y" pair...