Here is a list of those AutoLisp layer group codes for your reference.
;;
;; LAYER group codes
;;
;; Group codes -   Description
;;
;; 100 - Subclass marker (AcDbLayerTableRecord)
;;
;; 2  -   Layer name
;;
;; 70 - Standard flags (bit-coded values):
;; 1  = Layer is frozen; otherwise layer is thawed
;; 2  = Layer is frozen by default in new viewports
;; 4  = Layer is locked
;; 16 = If set, table entry is externally dependent on an xref
;; 32 = If both this bit and bit 16 are set, the externally
;;      dependent xref has been successfully resolved
;; 64 = If set, the table entry was referenced by at least
;;      one entity in the drawing the last time the drawing
;;      was edited. (This flag is for the benefit of AutoCAD
;;      commands. It can be ignored by most programs that
;;      read DXF files and need not be set by programs that
;;      write DXF files)
;;
;; 62 - Color number (if negative, layer is off)
;;
;; 6 - Linetype name
;;
;; 290 - Plotting flag. If set to 0, do not plot this layer
;;
;; 370 - Lineweight enum value
;;
;; 390 - Hard-pointer ID/handle of PlotStyleName object
;;

Also a fun routine a friend coded up once came to mind (not sure why), so I thought I'd post it just for fun.

Hey guys, it's been a while since I've posted in here. Someone using IntelliCAD 9.2 found a lisp that I posted back in 2003 for creating a true size set of railroad tracks. It still works fine for me testing in AutoCAD 2020 but he seems to be having an issue where it fails on the third polyline selected. If I were to write this lisp today I would definitely go about it differently, but really have no desire to rewrite it.

So, if anyone here can test in Intellicad and determine why it fails on the third running of it in the same file, I'd appreciate it. Just load the file, run the RRTRAX command, select  a polyline. I believe this was originally written prior to LWPOLYLINE objects, so to update it to work with them it converts those to the old heavy polyline then converts it back when done.

Thanks!

Those under NDA who tell: pp slappage

O.o

Perfect! Thank you very much!

I'm looking to pick objects and have their layers set to no plot.

I dont have a full working understanding of Lisp (or any programming), but I've generally managed to fudge things together based on others hard work and some trial and error.... But not this time!!

More often than not i'll be selecting entities nested within a block/xref, so have been looking at doing it via 
(vla-put-Plottable objectLayer :vlax-False)
But this is my first foray in to VLA, and I can't get my head around the object grouping & syntax order.

I've tried lots of variations, so this might not be the 'closest' I've come, but the autocad error isnt really helping me figure things out. Currently I have;

(defun c:NoP ( / doc enm obj objLayer)
 (setq doc (vla-get-activedocument (vlax-get-acad-object)))
 (while (setq enm (car (nentsel)))
   (setq obj (vlax-ename->vla-object enm))
   (setq objLayer (vla-get-layer obj))
 )
 (vla-put-Plottable objLayer :vlax-False)
 (princ)
)
The autocad error returns the correct Layer name, but it's obviously not getting it the way I want it to.

Select object:  ; error: bad argument type: VLA-OBJECT "LayerName"
Do I need to look at retrieving a full list of layers at some point?
Is it failing because the Command is set up to get a list of layers, but then I'm processing it as if there's only one? Or am I just way off?

Thanks in advance for any pointers!