It seems simple but I am not yet getting it on how to use entget to retrieve values from the Extended Dictionary of an AutoCAD object.

(entget (car (entsel)))

works, and shows e.g.:

(
  (-1 . <Entity name: 17812cb4670>)
  (0 . "LWPOLYLINE")
  (5 . "83F")
  (102 . "{ACAD_XDICTIONARY")
  (360 . <Entity name: 17812cb4680>)
  (102 . "}")
  (330 . <Entity name: 177903809f0>)
  (100 . "AcDbEntity")

Now I guess that numbers like 17812cb4680 are identifiers to objects that may contain data, but you cannot just give such a number to entget, like:

(entget 17812cb4680)

I can save a selection in a variable:

(setq  x  (entsel))

which returns something like an ID plus x-y-z coordinate:

(<Entity name: 17812cb4670> (121311.0 486438.0 0.0))

Evaluating that variable normally needs just typing the name, but in Autocad it needs an exclamation mark:

!x

but using that variable in entget is not straightforward, these all fail:

(entget x)
(entget 17812cb4670)
(entget !17812cb4670)
(entget (<Entity name: 17812cb4670> (121311.0 486438.0 0.0)))

(entget  '(<Entity name: 17812cb4670>))

Apparently, that little what I know about Lisp works differently in AutoCAD. I searched a lot for solutions but could not find it.

Any help is very much appreciated.