Using Layers to Organize Your Drawing - AutoCAD 2011 and AutoCAD LT 2011: No Experience Required - page 296

TIP It's a generally accepted best practice that an object's color, line-
type, lineweight, and transparency should all be By Layer. however, it's not
uncommon to receive a drawing with lots of object overrides (usually from
a third-party, and usually irrelevant to anyone else). Use the SETBYLAYER
command to clean this up quickly.
In this chapter, you have seen how to assign colors and linetypes to layers in
order to control the way objects on those layers appear. That is the rule to fol-
low. When objects are assigned properties that vary from those of their layer, the
result can be confusing to someone working with your drawing file, because the
objects don't appear to be on their assigned layer. If the object's properties match
those of another layer, you can mistakenly think the object is on that layer.
Making a Color or a Linetype Current
If you look at the Properties panel for a moment, you'll see more such lists to
the right of the Layer drop-down list. The first three are the Color, Linetype, and
Lineweight controls. You use these tools to set a color, linetype, or lineweight to be
current. When this is done, each object subsequently created will be assigned the cur-
rent linetype, lineweight, and/or color, regardless of which linetype, lineweight, and
color have been assigned to the current layer. If, for example, the A-DOOR layer is set
as the current layer and the Dashed linetype and green color are assigned as current,
any lines drawn are dashed and green but still on the A-DOOR layer. This isn't a good
way to set up the system of layers, linetypes, and colors because of the obvious confu-
sion it will create in your drawing, but beginners often accidentally do this.
The best way to maintain maximum control of your drawing is to keep the cur-
rent linetype, lineweight, and color set to ByLayer, as they are by default. When
you do this, colors and linetypes are controlled by the layers, and an object takes
on the color and linetype of the layer it is on. If this configuration is accidentally
disturbed and objects are created with the wrong color or linetype, you can cor-
rect the situation without too much trouble. First, reset the current color, line-
weight, and linetype to ByLayer by using the drop-down lists on the Properties
panel. Next, select all problem objects; then use the Properties palette or Quick
Properties panel to change the linetype, lineweight, or color to ByLayer. They will
take on the color, lineweight, and linetype of the layer to which they have been
assigned, and you can quickly tell whether they are on their proper layers.