The Task Force on CAD Layer Guidelines
Layer Name Format
Layer Formats
Long Format
Modified Long Format
Short Format
Modified Short Format
Major Groups
Minor Groups
Modifier
User Definable Fields
Building and Drawing Information Layers
Layers for Elevations, Sections, Details,
and Three-Dimensional Drawing
Prepared by:
The Task Force on CAD Layer Guidelines
Sponsored by:
The American Institute of Architects
The American Consulting Engineers Council
The American Society of Civil Engineers
The International Facility Management Association
The Naval Facilities Engineering Command
The United States Army Corps of Engineers, and
The Department of Veterans Affairs.
Members of The Task Force on CAD Layer Guidelines:
Representing the American Institute of Architects, Practice Committee:
Michael Scheley, AIA, task force chairman,
FM:Systems, Raleigh, North Carolina
Richard Buday, AIA, Buday Wells Architects,
Houston, Texas
Mark Lauden Crosley, AIA, San Francisco,
California
William Garbus, AIA, IBM Corporate
Real Estate Construction Staff, Stamford, Connecticut
Terrence G. Schilling, AIA, Irvine,
California
Representing the American Consulting Engineers Council:
Timothy O'Conner, PE, Automation Integrators,
Birmingham, Michigan
Hal Parks, PE, Cater and Parks, Birmingham,
Alabama
Alan G. Steinle, PE, Duffield Associates,
Wilmington, Delaware
Representing the International Facility Management Association:
Thomas Kvan, Strategic Management
Consulting, Alexandria, Virginia
Representing the American Society of Civil Engineers:
Charles Moone, M.ASCE, Willdan Associates,
Anaheim, California
Representing the Naval Facilities Engineering Command:
Dana K. Smith, AIA
Representing the United States Army Corps of Engineers:
Edward Middleton, Ph.D.
Representing the Department of Veterans Affairs:
Randy Holt
With Assistance of the staff of the American Institute of Architects:
Charlotte Franklin, senior director, Practice
Christopher R. Clark, AIA, director, Practice
Elizabeth M. White, assistant director, Practice
CAD Layer Guidelines are published by:
The American Institute of Architects Press
Washington, D.C.
Layer
Formats
The Layer Guidelines are organized
as a hierarchy. This structure makes the list
easier to use and accommodates future expansion. Layer names are
alphanumeric and use easy to remember abbreviations such as A-DOOR for
architectural doors, A-WALL for architectural walls, and E-POWR for electrical
power.
Two formats are defined for layer names: a long format using 6-16 characters
and a short format using 3-8 characters. The short format reduces keystrokes
and can be accommodated on systems restricted to 8-character layer names.
However, the long format provides greater readability. Either format may be
used, but consistency should be maintained within a project.
Layer names are mnemonic in character to improve ease of use. In the long
format, hyphens are used to separate major group, minor group, and modifier
to improve readability.
Note:
Where the linetype or color specification modifications are used, the hyphens
are replaced
by these. In the short format these modifications are appended to the end of
the short format
layer name but preceding the user-defined field which is itself always preceded
by an hyphen.
For example: A-WALL-HALF entities of linetype "Center" and color "Yellow" (color
#2) would
become ACWALL2HALF in long format and AWAHAC2 in short format. If a user-defined
METL is added to the short format layer the result is AWAHAC2-ME
Long format layer names can be automatically converted to short format layer
names by combining the major group code, the first two characters of the minor
Groups characters of the modifier. For example, A-WALL-FULL is converted to
AWAFU. It is quite possible that many CAD vendors will implement a layer
"alias" feature, providing automatic translation between short form and long
form layer names, thus providing the benefits of both formats.
Long Format
Major Group-1 character. This categorization breaks the list into
manageable sections, using the divisions of architectural, structural,
mechanical, plumbing, fire protection, electrical, civil engineering
and site work, and landscape architecture.
Minor Group-4 characters. Generally minor groups designate
assemblies or construction systems such as walls, doors, ceilings,
or electrical power.
Modifier-4 characters (optional). This is an optional field
for further differentiation of minor groups such as
distinguishing full height walls from partial height walls
or emergency lighting from general lighting.
User Defined-1-4 characters (optional). This
optional field may be used to accommodate
special project requirements.
X-XXXX-XXXX-XXXX
Examples A-WALL Walls
A-DOOR-IDEN Door Numbers
Modified Long Format
A linetype and color specifier are inserted in place of the first two hyphens
of the unmodified long format layer name The linetype or color specifier can
each be used alone. If either one is not used in the long format then the layer
name simply has no modifications there and the hyphen remains.
Linetype specifier - 1 character. (Optional, an hyphen if not used).
Color specifier - 1 character. (Optional, an hyphen if not used).
XCXXXX2XXXX-XXXX
Examples: ACWALL2 Walls
ACDOOR2IDEN Door Numbers
Short
Format
Major Group - 1 character
Minor Group - 2 characters
Modifier - 2 characters (optional)
User Defined - 1-2 characters (optional)
XXXXX-XX
Examples: AWA Walls
ADOID Door Numbers
Modified Short Format
A linetype and color specifier are appended to the unmodified short format
layer name prior to the user-defined field if one is used. If a modifier is not
used then an hyphen is put in its place prior to the linetype and color specifiers
When the user-defined field is used it is always preceded by an hyphen. The
linetype or color specifier can each be used alone. If linetype is not used with
color then an hyphen is put in its place in the layer name. If color is not used
it
is simply ignored and the layer name is constructed without it.
Linetype specifier - 1 character (optional, an hyphen if color is used alone)
Color specifier - 1 character (optional)
XXXXXC2-XX
Example: AWA-C2 Walls
ADOIDC2 Door Numbers
Major
Groups
Although the major groups correspond to the traditional discipline designations
used in construction document sheet numbering, they are not intended to suggest
or control which member of the design team draws which objects. For example,
the column grid would be placed on layer S-GRID regardless of whether it was
drawn by the architect or structural engineer.
Eight major groups are defined in the unmodified guidelines:
A Architecture, Interiors, and Facilities Management
S Structural
M Mechanical
P Plumbing
F Fire Protection
E Electrical
C Civil Engineering and Site Work
L Landscape Architecture
G General, Border Sheets, etc., not specific to a discipline,
(a modification to the CLG)
Linetype Specifier (modification to the CLG)
Linetype specifier is a single character that replaces the hyphen immediately
after the major group of the long format layer name. This modification is
required if changes of Xref'd entity linetypes will be made in the current drawing.
This is a limitation of AutoCAD. Since it is hard to predict such needs in
advance it is best to avoid rework by always specifying layer linetype and using
"bylayer" for entity linetype. The number of linetypes available is limited to
the
number of valid characters that can be used. The characters used and their
associated linetype is left to the user.
Minor
Groups
Minor groups subdivide major groups on the basis of construction system or
type of information. For example, the architectural major group contains minor
groups for walls, doors, floors, ceilings, furniture, and equipment.
Color Specifier (modification to the CLG)
Color specifier is a single character that replaces the hyphen immediately
after the minor group of the long format layer name. This modification is
required if changes of Xref'd entity colors will be made in the current drawing.
This is a limitation of AutoCAD. Since it is hard to predict such needs in
advance it is best to avoid rework by always specifying layer color and using
"bylayer" for entity color. The number of colors available is limited to the
number of valid characters that can be used. The characters used and their
associated color is first numeric and then alphabetic. For example: Red=1,
Yellow=2, Green=3, etc. through White=7. The colors in AutoCAD are purely
numeric from this point on. After color number 9 the color specifier is
alphabetic, i.e. 10=A, 11=B, 12=C, 13=D, 14=E, 15=F, etc. The number of
colors available is limited to the number of valid characters that can be used.
Modifier
A modifier may be added to a layer name for further differentiation. For example,
walls (A-WALL) may be categorized as full height (A-WALL-FULL), partial
height (A-WALL-PRHT), or movable (A-WALL-MOVE).
The modifier is optional and need not be used when the minor group layer name
alone will suffice. For example, a simple project might be accomplished using
only the layers shown below:
A-WALL AWA Walls
A-DOOR ADO Doors
A-GLAZ AGL Windows, Window Walls, Curtain Walls, and Glazed Partitions
A-FLOR AFL Floor Information
A-CLNG ACL Ceiling Information
A-ELEV AEL Interior and Exterior Elevations
A-DETL ADE Details
A-PFLR APF Floor Plan
A-PCLG APC Reflected Ceiling Plan
CAD drawings may contain a combination of layer names with and without
modifiers. In the example below, A-WALL contains all walls except partial
height and movable walls.
A-WALL AWA Walls
A-WALL-PRHT AWAPR Partial Height Walls
A-WALL-MOVE AWAMO Movable Walls
A-DOOR ADO Doors
A-DOOR-IDEN ADOID Door Numbers
A-GLAZ AGL Windows, Window Walls, Curtain Walls, and Glazed Partitions
The choice of using layer names with or without modifiers allows the
guidelines to be used in a straightforward, streamlined fashion for simple
projects that don't need the level of detail required for large complicated
projects.
User Definable Fields
The guidelines are intended to be open-ended. The user-defined field
allows additional layers to be added to accommodate special project
requirements. The user-defined field may be added after a modifier or in
place of a modifier. Below are some examples of user-defined fields:
A-DOOR-METL ADR-ME Metal Door
A-DOOR-IDEN-METL ADRID-ME Metal Door Number
A-FURN-PANL-MFR1 AFUPN-M1 Furniture Panels from Mfr 1
A-FURN-PANL-MFR2 AFUPN-M2 Furniture Panels from Mfr 2
A-WALL-01 AWL-01 Walls on 1st Floor
A-WALL-02 AWL-02 Walls on 2nd Floor
User-defined fields may be variable in length up to 4 characters for long format
layer names or 2 characters for short format layer names.
Building and Drawing Information Layers
Layer names for each major group are divided into two sections: building
information layers and drawing information layers.
Building information generally represents the physical form of the site, building,
or objects in the building This information is often shared between drawings.
Examples include walls, doors, light fixtures, and room numbers. Building
information may be either literal (such as walls) or symbolic (such as electrical
outlets) . Cross-hatching and identification labels such as room numbers are also
grouped with building information, using the modifiers "PATT" and "IDEN" since
this information is often shared between drawings.
Drawing information adds annotation, dimensions, and cross references and
usually is not shared between drawings. Examples include notes, dimensions,
annotative symbols, and tabulations. Drawing information layers are organized by
drawing type and type of information rather than by construction system.
For example:
A-PFLR-TTLB APFTT Sheet Title Block and Name
A-PFLR-DIMS APFDI Architectural Floor Plan Dimensions
A-PCLG-DIMS APCDI Architectural Reflected Ceiling Plan Dimensions
Layers for Elevations, Sections, Details, and Three-Dimensional Drawing
Special groups of layers within each major group are defined for elevations,
sections, and details:
*-ELEV *EL Elevations
*-ELEV-OTLN *ELOT Building Outlines
*-ELEV-PATT *ELPA Textures and Hatch Patterns
*-ELEV-IDEN *ELID Component Identification
*-SECT *SE Sections
*-SECT-MCUT *SEMC Material Cut by Section
*-SECT-MBND *SEMB Material beyond Section Cut
*-SECT-PATT *SEPA Textures and Hatch Patterns
*-SECT-IDEN *SEID Component Identification Numbers
*-DETL *DE Details
*-DETL-MCUT *DEMC Material Cut by Section
*-DETL-MBND *DEMB Material beyond Section Cut
*-DETL-PATT *DEPA Textures and Hatch Patterns
*-DETL-IDEN *DEID Component Identification Numbers
The modifier "-ELEV" can also be added to any minor group layer (A-WALL,
A-DOOR, etc.) to identify information only seen in 3D views. This facilitates
integrating three-dimensional CAD "models" with two-dimensional plan
drawings. For example:
A-WALL AWA Walls (in Plan View)
A-WALL-ELEV AWAEL Wall Surfaces (3D Views)
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