AutoCAD enables you to stack different parts of the drawing data base in the same way you would use sheets of mylar, you use AutoCAD's' electronic LAYERS as if they were the transparent layers of mylar by assigning different layer names, characteristics, colors to the differentiate the entities and blocks that you generate in your drawing. This functionality has been in AutoCAD since at least release 9 (note: I have been using AutoCAD since v2.6 but I started using layers in R9 so I am checking into this)

In order to use layers you must first create them. To do this you need to use one of two commands, DDLmodes or Layer. Lets first look at DDLmodes. The DDLmode (Dynamic Dialogue) interface has changed in release 14, along with all of the usual features, the interface has completely changed to be more like release 13's layer pull down in the standard tool bar. The push buttons have been replaced with the sun, padlock and light bulb. The new interface also has built-in paper space features that will freeze and thaw layers in current, new or all view ports.

To create a new layer, click on the NEW button and enter the new layer name in the highlighted field. With the new ways to manipulate layers, you need to scroll to find the layer color and line type editors. Click on the color field in the editor and the 256 color chart will appear. Once you have selected your color you can then select your line type and decide the disposition of your layer or make it current, for now give grid a line type of center and make grid the current layer. Now create 3 more layers, wall, beam and joist. Give grid a color of yellow, wall a color of blue, beam magenta and joist red and keep all line types continuous.. Set all colors and line types to be bylayer. Layer names can be have up to 31 characters and can have the hyphen, underline and the dollar sign as part of the name. You can not give a new layer an existing layers name. Now draw some grid lines and places a double line on the grid lines to show walls and then draw some beams and joist. All of this will be drawn in the plan view.

In order to change the current layer, one way is to open the DDLmodes dialogue box and click on the layer name of which you need to be current and then clicking on the current button. DDLmodes will also allow you to change the disposition of your layers either one by one or setting a selection set. Click on the Layers icon on the standard tool bar and select the wall layer and make it the current layer. Now click on the beam layer hold down the shift key and select the joist layer all of the layers between beam and joist will be selected and now you can change their disposition by clicking on any of the valid options. Click on one of the suns under the freeze in all viewports and all of the suns in the selected set will change into snow flakes indicating that the layers in the selected set are frozen and click on OK. The result is that only the wall layer which was not frozen is all that remains visible on our drawing.

You can turn layers on or off by clicking on the light bulbs under the on heading. A layer that is off can be the current layer, but when you draw on a layer that is off you will not see it nor will you be able to edit it. This differs from a layer that is frozen in that a frozen layer can not be the current layer therefore it can not be used to create an entity.

Layers that are locked can be used to create new entities that are visible on the screen however they can not be edited. Locked layers have a very powerful use. If you need an entity that you do not want changed but you will need to use it for construction lines or as a reference, entities that are locked can have their information listed, and other entities will recognize them for snapping.

The following summarizes the effects of layer states.