[ 2001-2 ]
Section 21 - Linda A.E.Cripps
content update: 12 February 2001
The National CAD Standard
Layer Naming Conventions
Layer Name Convention Information
The AIA CAD Layer Guidelines have been incorporated as part of the National
CAD Standard. The development of a standardized CAD layer system pre-dated
the work of the CSI's Uniform Drawing System. Rather than reduplicate the
wheel, so to speak, the committee on the UDS and the National CAD standard
decided to use the CAD Layer Guidelines under development by the AIA.
History of Standard Layer
In terms of implementation of the National CAD Standard, many offices
elect to continue with their prior layering systems, rather than adopt
the AIA CAD Layer Guidelines. Therefore, it is highly likely that an architectural
technician will be using an "office standard" for layering CAD drawings,
but it may not be the AIA standard. As the curriculum development for AET
241 began prior to the finalization of either the AIA Layer guidelines
or the National CAD standard, a decision had to be made several years ago
concerning a layering system. A course standard layer system was developed
that uses a logic similar to the AIA system, but is not identical to it.
In considering updating all of the course CAD files to a different layering
system, I encountered a similar dilemma as most offices face at the moment.
The course will continue to use the "course standard layer system",
rather than implement the AIA system. This is because:
All offices have standards, but not necessarily the AIA standard
The course layer system is similar in structure and complexity as the AIA
The course layer system is simpler to interpret than the AIA standard
Existing course CAD resources would require less revision
Documentation exists for the course standard that is easily available to
Short Summary of AIA CAD
Layer Guidelines [top]
The student should refer to the Jefferis textbook in Chapter 3 - Applying
AutoCAD Tools to Commercial Drawings for an more extensive discussion of
AIA Standardized Layer Names. There is also an online
lecture on the AIA Standardized Layer names.
Like the UDS file naming system, the AIA layer guidelines were developed
to provide a standardized system that could be adapted to small and large
projects, and has some built in flexibility. Therefore, it has both "short
format" and "long format" names, and in addition to pre-defined elements,
it allows for the addition of "user-defined" modifiers, to customize the
basic system to particular office or project needs.
The standard format for AIA long format layer names is:
where "DD" represents the major group identification which corresponds
to the drawing disciplines - "A" for Architectural, "C" for Civil, "E"
for Electrical, etc. The AIA system allows for the use of one or
two characters for the discipline designators, depending upon specific
office needs. The next four characters "MJGP" are defined as the
"major groups" within the discipline identifcation. Some AIA major groups
are "FNDN" , "WALL", "SLAB", etc. The next four characters "MJGP" are termed
the "minor groups" to further subdivide the major groups.
The layer name need not contain the last four characters, "USDF", as
this is the user-defined modifier and is added at the user's discretion.
C-WALL-CMU would be the layer for the concrete masonry units in
the exterior walls on structural drawings.
A-WALL--CMU would be the layer for the concrete masonry units in
the exterior walls on the architectural drawings, while
A-WALL-GYBD would be the layer for the gypsum board construction
in the exterior walls on the architectural drawings, and
AI-WALL-GYPD-REN would be the layer for gypsum board renovation
in the exterior walls of architectural interiors drawings
Short Summary of Course Layer
The course layer guide lines follow a similar
structure as the AIA short format names.
The course standard format is:
"D" is the category for discipline, in this course this will always be
"A". What differs slightly from the AIA system, are the specific definitions
fo the major groups and minor groups, "MJGP" and "MNGP" categories.
As the AIA standard has evolved and the oppotunity for revision of the
class standard has occurred, these differences are becoming fewer and fewer.
The minor group names and modifiers for the course layer system are
based on the construction components and loosely modeled on the CSI 16
Division Masterformat categories - SHFT - shaft wall, STFM - structural
frame, STAR - stair, DOOR - door, SPEC - specialites, etc.
The course will make use of the "USDF", user-defined layer category
only on the tenant plan drawings.
At the end of this reference page, there are links to the documentation
that exists for the course layer guidelines.
Some examples as above would be:
A-DOOR-UNIT would be the layer for the drawing elements of a door
A-DOOR-IDEN would be the layer for the door mark symbol., A-GRID-DIM
would be the layer for the dimensions of the structural grid, while
A-ANNO-DIM would be the layer for the other dimensions of the drawing
Notes on Colors and Layers
Prior to AutoCAD 2000, the color definitions for the layers were significant
as they directly correlated to the plotter formatting for determining the
lineweights on the drawing. In the current version of AutoCAD, the lineweight
can now be defined as a drawing entity property, and so the strict adherence
to the standard layer colors is not required to produce a correctly plotted
drawing. It is recommended that the standard layer colors in the prototype
drawings be used. They are best seen on a white display background, rather
than a black one. ( This can be modified in the "Tools - Preferences -
Display" menus )
Course Layer Guideline References
Three different documents on the course layer guidelines are available,
both by downlink from this web page, or from the Asylum H:\aet241_cripps
Layer Naming Conventions - Explanation
of the course layer name system
Word 2000 format
Layer Naming - Reference for Complete
Word 2000 format
[cadlyltn_022.doc] NOTE: This document is UNAVAILABLE for Spring
2002 term.it is under revision to consider integration of v2 of
National CAD Standard.
Layer Naming - References for Drawing Types
Word 2000 format - Detail
Word 2000 format - Plan
Word 2000 format - Elevation
© Y2K+1 - L.A.E.Cripps. All rights reserved.