Use this procedure to obscure or “hide” a region of linework in relation to other linework. This feature is chiefly useful when you want to indicate that one entity extends behind or beneath another entity that you want to display in the foreground. The obscured linework is placed on the layer specified by the HIDDEN layer key. Once you have begun the Obscure command, you can also specify two corners of a rectangle to use.
The obscured region is delineated with a dashed line. You can select it (or its component segments) separately from the linework it was part of before being obscured.
Obscuring linework with a block