Layers are like transparent overlays on which you organize and group different kinds of drawing information. Most CAD programs utilize layers. Layers, in CAD drawings, are a management tool used to organize data. All CAD files available from the 3-D Project have one active layer.
The layer naming convention has similarities with the file naming convention. A minimal twelve-character length string is used in the layer name. The first character designates the discipline code, the same as in the file name.
The second field is the Major Group Field. The major group field is four characters in length and is used to represent the "building" system. Once again since most broadcast equipment has not been categorized in the CAD Layer Guidelines the Major Group designation EQPM is used most commonly for files available at the Web site. EQPM is used to designate "equipment".
After the second layer information field a single character "-" is used as a separator. Following this separator is the user-defined field. This is a variable length field and is used to describe the drawing object. All drawing objects of the same type will have the same description, regardless of their model differences.
This naming convention was chosen to better manage drawings with multiple "object file" inserts. For example: all types of microphones would be on layer "X-EQPM-Microphone". In this manner all microphones in the drawing can be accessed easily as they reside on the same isolated drawing layer. A more detailed tutorial on drawing management is available on the Web site.
The objects created on a layer have common properties including colors, linetypes, and lineweights. An object can assume these properties from the layer it is drawn on, or properties can be specifically assigned to individual objects.