Using Named Objects in AutoCAD
One thing that can make AutoCAD interesting is the somewhat cavalier naming conventions used in the program’s documentation. For years, elements such as lines, arcs, and other graphical items were called entities, but then they started being called objects. Fair enough, but object has also long been used to define certain nongraphical components of a drawing — items you’d hardly even consider to be objects — and those are the kind of named objects you will see here.
Hidden in the innards of every AutoCAD drawing file is a set of named objects, which are organized into symbol tables, and the properties that are common to all AutoCAD objects are defined in these tables. For example, all line objects in a drawing are stored on one or more layers, so a layer property is common to all lines and is defined in the layer table. But the coordinates that define the start and end points of a given line are unique to that line (or they should be!), so the coordinate properties aren’t common to all lines.
A layer is one example of a named object. The layer table in a given drawing contains a list of the layers in the current drawing, along with the settings for each layer including the color, linetype, and on/off setting.
Named objects don’t appear as graphical objects in the drawing. They’re like the hardworking behind-the-scenes pit crews who keep race cars running smoothly. These named objects are the ones you’re likely to use most often (including cross-references):
- Text style
- Table style
- Multileader style
- Multiline style
- Dimension style
- Block definition and xref
When you use commands such as LAyer, LineType, and DimSTyle, you’re creating and editing named objects. After you create named objects in a drawing, the AutoCAD DesignCenter or Content Explorer give you the tools to copy them between drawings.
Donald Trump might believe otherwise, but you can have too many properties (at least in AutoCAD). You may have created layers or loaded linetypes, text, or dimension styles that you don’t use. When you suspect that you have some of these superfluously named objects in the drawing, the PUrge command can help you get rid of them.
Click the application button to display the Application menu. Choose Drawing Utilities →Purge to open the Purge dialog box. You can click the plus sign (+) beside a category to purge individual items, or you can click Purge All and get rid of tons of stuff all at one time. Visit the online Help system for more about purging.