Rotate ucs on 3d object

[Travaci]

Hello everyone,
I want to do the following briefly.
I'll specify two points, and it will automatically find the third point, then rotate it on the Z axis.
This should work in both UCS and WCS.
...
(setq n1 (getpoint))
(setq n2 (getpoint))
(command "_.ucs" "_3p" n1 n2 n3)
(command "_.ucs" "ZA" n1 n2)
...

[dexus]

If you press enter with n3 the Z axis seems to keep pointing in the same direction, so this like works for me:

(if
  (and
    (setq n1 (getpoint))
    (setq n2 (getpoint))
  )
  (command "_.ucs" "_3p" n1 n2 "")
)