Each object in Autodesk Civil 3D has a base layer on which the object physically resides, and component layers that control the display of object components, such as surface triangles or contours.
The base layer is defined in the Drawing Settings or at creation time. The component layers are defined in the object styles.
You specify the default base layers for objects on the Object Layers tab of the Drawing Settings dialog box.
When you create an object, you can accept the default or specify a new layer. The base layers are used only for the main object types, such as surfaces and alignments.
Because the object physically resides on the base layer, you can control object visibility by changing the layer state. For example, if you turn off the base layer for surfaces, all surfaces are turned off in the drawing.
You specify component layers on the Display tab of the <object> Style dialog box. The following example shows layers used for alignment components:
The component layers allow you to work with objects as if parts of them are located on different layers.
Objects are physically created on the base layer, but the display of components is governed by the associated component layers. Each object component uses the visibility settings for the component layer (such as on/off), as well as the color, linetype, lineweight, and plot style for the layer if the various Component Display settings are set to ByLayer.
If you are accustomed to controlling objects by manipulating layers, you may want to set the various object style Component Display settings to ByLayer. Then you can simply change the layer settings using the AutoCAD Layer command rather than editing styles to change the color, linetype, lineweight, or plot style of an object component.