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Both layer off/on and layer freeze/thaw affects the visibility of layers. The main difference between them is that if some layers are in off state you can still copy all the elements from those layers one cad file to another whereas if some layers are frozen you won't be able to copy the elements in those layers into another cad file. So freezing layers is useful if you just want to copy certain layers with elements into another cad file and leaving the unnecessary.
Turning layers OFF essentially turns those vectors (the stuff you see on the screen) off for display, but they are still maintained in AutoCAD's Display List. The DL is a special area of RAM which Acad uses to track vector data. Because the Display List is in fast RAM, we can now pan all around a drawings without AutoCAD needing to recalculate and translate drawing data (e.g. a green line from pt A to pt. B) into on-screen vectors. This Regen converts drawing vector data into screen vector information, which is why it's much slower than a Redraw (which only refreshes the on-screen data). Older versions of Acad had (I think) a 16-bit display list, which was tiny in today's standards. Your screen "memory" could only be so big before the DL needed refreshing - you needed to do a regen every time you panned out of bounds. AutoCAD R12 (?) introduced the 32-bit display list, which made stuff like Zoom VMax possible. You could pan/zoom with wild abandon without as many regens. Keeping layers OFF tends to slow things down in large drawings, since AutoCAD is (I believe) just drawing over those vectors with a complimentary color (i.e., the two screen vectors visually cancel each other out). When they are Frozen, screen redraws run at full speed. When you freeze a layer you remove those objects on that layer from the display list completely. Thus, you decrease the memory footprint for the display list, and can really keep Acad running at top speed. Likewise, when you Thaw a layer, Acad needs to add that info back to the Display List, incurring a possible painful Regen. In R14, AutoCAD (finally) introduced the display list to Paperspace, so that you can pan around in Pspace without incurring a Regen penalty. The upshot of all of this is that you should Freeze layers which you want to keep them from displaying at most times. Use ON/OFF when you wish to toggle layer visibility quickly.
both of them allows to hidden the layout:
- "layer on-off" objets are visible or hidden, just that, Is a good choice for drawings with a lot of layers.
- "layer freeze on/off" objects can not be deleted or edited, remains in the layer, are frozen in place.
IF WE DO WORK XRED WE FREEZ SOME LINE MEAND IT DOESNT DLT IR DNT SHOW ON SCREEN AND WHILE WE DO LAYER OFF WE DO DONT DELATE BUT IT WILL SHOW OFF
