Autodesk AUTOCAD 2006, Command Reference Manual, Page: 443 / 1490

Hidden
Indicates that the file is hidden; you cannot see or use it unless you know
its name.
System
Indicates that the file is a system file. A drawing cannot have the System
attribute set.
Summary Tab (Drawing Properties Dialog Box)
Displays properties such as author, title, and subject that are predefined. For
example, you can add keywords to all your drawing files and then use
DesignCenter
™
to search for all drawing files with a particular keyword.
Title
Specifies the title you want to use when searching for this drawing. The
title can be different from the drawing file name.
Subject
Specifies the subject of the drawing. You can use the subject name to group
drawings that have the same subject.
Drawing Properties Dialog Box | 419