If the out of box layers are not what your company wants to use, or you have created new system definitions or wall styles and need to create a new layer for them here is an outline that can help guide you on your way. You will want to do this inside your company template file, if you don't have one either make one or use the out of box .dwt.
NOTE: You can do this in your AutoCAD Architecture but to reduce confusion I am using ACAD MEP as my example.
To open the Style Manager, click on the Manage tab > Style & Display panel > Style Manager drop-down > Style Manager.

In the Style Manager dialog box, you will see two panels. One the left side, it shows your drawing file and the styles within it. The right side is going to show you information about the selected style.

In the left Panel expand Multi-Purpose Objects. Expand Layer Key Styles. You should see MEP Object – AIA 256 Color. You will need to make a copy of this so you can start to customize your own Layer Keys for your System Definitions.
To make a copy of MEP Object –AIA 256 Color, select on it then right click > copy. Right click again and click paste. Rename your new Layer Key Style.

Select on your new Layer Style, from the right side click on the Keys tab to start adding your Layer Keys.
NOTE: In order for you to use the MEP Object AIA standards you need to keep within the layer key standards which is the P-SY-PIPE-, if not, your layer key and system definition will not marry up.

To add Layer Keys to your new style, click the Add button and enter in a name for the new Layer Key and click the OK button.

Navigate to your newly created Layer Key in the list to modify the layer settings. Hint- click on the Description column twice to sort by description. All new Layer Keys will not have a description so it will sort it to the bottom of the list to make it easier for you to find.
You will need to modify the following layer settings for each layer key:
- 1- Description – this can be anything describing this layer.
- 2- Layer
- 3- Layer Color- Click on the Color to change the layer color.
When clicking on the Layer browse button you will see a Layer Name dialog pop up, where you can modify the Layer Name. Remember it’s very important to keep the standard Layer Name which is the P-SY-PIPE-. Click the Apply then the OK button. I suggest creating a layer key applying it to a system definition and then testing it in the drawing file before completely creating all your layer keys inside your layer style.

Verify that your drawing or if your company has a template open that up and set the Layer Key style to the one you just created.
At the command line type UNITS
Click on the Layering Tab.
Make sure that your Layer Key Style is set to the correct Layer Key Style.

Make sure the you put a check mark next to, Always import layer key styles when first used in drawing and Save as Default. This will help to ensure you are always using your custom Layer Key Style.
