With C3D, it seems that the big push is toward the NCS layer naming system. What is NCS and of what benefit is it to you? The following is written using NCS 3.0 as the basis. Find out more after the jump.

Around the world there are quite a few CAD Standards. The ISO (International Organization for Standardization) has a layer naming format (ISO 13567). The BSI (British Standards Institution) also has a layer naming syntax which is pretty much just ISO’s (BS 1192) and in the states there is the NCS layer naming syntax. NCS stands for National CAD Standards and although it is primarily known for its Layer Naming syntax, there is MUCH more to it than that. The NCS got its start a few years back by pulling together the CAD Layer Guidelines from The American Institute of Architect’s, the Construction Specification Institute’s Uniform Drawing System, and the CADD/GIS Center’s Plotting Guidelines, as publicized by the U.S. Department of Defense CAD/GIS Technology Center.

See there! The layer naming comes from Architects and as all Civil guys know, nothing good comes from Architects.

Well there is always an exception to the rule and as we investigate this naming format more fully, I think you will agree with me how versatile it really is.

The Concept

The concept behind the NCS layer naming format is the organizational structure called the ‘tree structure’. One of the most common examples of the ‘tree structure’ is found in Windows Explorer. Files (data) stored on a computer are not organized in this method (ever heard of defrag?) but the presentation to us is the ‘tree structure’. You have drives, main folders, and then sub-folders and sub-folders of sub-folders, etc. The same concept is applied to the naming of a layer.

The Format

Just as you have drives, we have disciplines. EVERY layer in a drawing belongs to a discipline just like every file must have a drive location. Then every layer must belong to a major group just as every file must have a name. Let’s look at this more fully.

Discipline Designators

A discipline designator is a one or two letter designator that defines the discipline that the layer belongs to. Remember, EVERY LAYER in a drawing belongs to a discipline. Since the NCS is established for every AEC discipline, then there are many designators that we will never use. The following figure organizes the most common disciplines into a hierarchy.

Discipline Hierarchy

Major Discipline Designator

Discipline

G

General

H

Hazardous Materials

V

Survey/Mapping

B

Geotechnical

C

Civil

L

Landscape

S

Structural

A

Architectural

I

Interiors

Q

Equipment

F

Fire Protection

P

Plumbing

D

Process

M

Mechanical

E

Electrical

T

Telecommunications

R

Resource

X

Other Disciplines

Z

Contractor/Shop Drawings

O

Operations

Minor Discipline Designators

Although the Major Discipline designator defines which discipline, I prefer to also use the optional Minor Discipline Designator. The reason is then you can control not only what type of work each layer belongs to (grading, environmental/erosion, site, etc.) but also for survey’s we can quickly tell you what kind of survey the layer belongs to (GIS, Field shot, aerial, etc.).

Minor Discipline Designators
CD	Civil Demolition
CE	Civil Environment
CG	Civil Grading
CR	Civil Roadway
CS	Civil Site
CU	Civil Utilities
CJ	Civil Junk
CK	Civil Miscellaneous
VA	Aerial Survey
VF	Field Survey
VI	Digital Survey
VJ	Survey Junk
VK	Survey Miscellaneous

 

Major Group

After we have defined the discipline for the layer, now we have to assign the layer a name. To do this we group common layers together starting with what is referred to as the Major Group. Just as you have Major Folders (C:\Windows, C:\Program Files\, etc.) you have types of construction that can be grouped together (CS-ROAD, CG-TOPO, CU-SSWR). First rule of all groups, major and minor, is that they are ALWAYS EXACTLY FOUR CHARACTERS IN LENGTH. This provides legible consistency and controls the order of these layers in the layer dialog box (let alone great automation potential). The NCS defines many Major Groups and if you strictly adhere to the NCS, you are not allowed to create your own but what we are reviewing is the naming format, not so much rules. As a popular movie quote says, “They are more like guidelines anyway”.

Just as the drive and the file/folder name are separate so the Discipline designator and the major group are separated using a hyphen “-“.

Minor Groups

Within a tree structure, you can be as organized or as cluttered as you wish past these two first stages (Drive and file name). The same applies to the NCS layer naming format. If we want to place all the roadway objects (edge of road, centerline, curb lines, etc) on one layer we can (CS-ROAD). Of course, the best practice is to break these up a bit. However, they all still belong to the same major group of CS-ROAD (Civil, Site, Road). Therefore, the purpose of minor groups (CS-ROAD-ASPH, CS-ROAD-CNTR, CS-ROAD-CURB).

You can even get more organized than one minor group. For example, you want to separate the face of curb and back of curb on different layers. However, both the back and the face are part of the CURB group, right? So you would have CS-ROAD-CURB-BACK and CS-ROAD-CURB-FACE. Obviously, just as each sub-folder name is separated from the parent folder so each group is separated from the other with a hyphen “-“.

Note two other things:

1. All layers are in uppercase.
2. ALL GROUPS ARE FOUR CHARACTERS LONG

Are you starting to see the power of the format?

Status Fields

Just as a file can have separate properties from the folder it belongs to (i.e., read-only) so a layer that belongs to a specific group can be in a different status from the rest of the group.

D	To be demolished
E	Existing
F	Future
T	Temporary
X	By others (NIC)
1-9	Phase numbers

For example, you have the field survey file showing a road curb. However, some of that curb is to be removed. The curb that is to be removed is still part of the major group of road and the minor group of curb but its status has changed. It is going to be demolished. Therefore, the layer name will simply have the status “D” added to the end.

Some points to remember about a status field:

1. It is not required but is only added when necessary. For example, the status field “E” is not required for each survey layer. However, for an existing profile grade this would be appropriate (CK-GRAD-E / Civil, Miscellaneous, Grade Line, Existing).
2. A Status Field is always found at the end of the layer.

Just as all other parts of a layer are separated from one another by a dash so the status field is separate from the group with a hyphen “-“. USE ONLY THE STATUS FIELDS PROVIDED.

Examples

Let’s look at a few examples of this format at work. For a proposed asphalt road edge layer we would have the following:

CS-ROAD-ASPH

Notice that the minor group actually defines the material used for the road. If this does not matter we can use “EDGE” as a minor group. However, it is encouraged to use the material groups. For example, we can have the layer above and the layer below in one drawing.

CS-ROAD-CONC

More complex options

Road, Drives, and Parking Lots versus Pavement

With a drawing containing a proposed concrete parking lot, a proposed gravel drive, and a proposed asphalt road it gets a little more complicated. The question comes down to whether or not you want/need to separate each infrastructure on its own group or not. If the answer is yes, then you would have three major groups spreading the layers out in the pulldown but providing flexibility if you need to freeze objects from one major group but not the other. Let’s look at the edge of pavement layers for each.

The parking lot edge of concrete pavement layer:

CS-PRKG-CONC

The drive edge of gravel pavement layer:

CS-DRIV-GRVL

The road edge of asphalt pavement layer:

CS-ROAD-ASPH

If the answer to the above question is no, each infrastructure does not need to be on its own major group then you would still have three layers but under one major group – the Pavement major group.

The parking lot edge of concrete pavement layer:

CS-PVMT-CONC

The drive edge of gravel pavement layer:

CS-PVMT-GRVL

The road edge of asphalt pavement layer:

CS-PVMT-ASPH

The last option is if you did not want/need to separate the pavement materials into separate layers than the layer for all would be as follows:

CS-PVMT-EDGE

Paved walks

Another example where some might get confused is that the sidewalk could fall under the pavement major group or the sidewalk major group. However, again applying some common sense and forethought about that specific project will help us know which major group the sidewalk would fall under. If for any reason the sidewalk NEEDED to be split from the rest of the pavement group then by all means use the sidewalk major group. That is what it is there for. Nevertheless, more often than not the sidewalk is a portion of the paved areas shown (concrete pads, concrete sidewalks, etc.). In these more common cases the concrete sidewalk would be found on the CS-PVMT-CONC layer. In rare cases where the sidewalk is a major component of the project (i.e., a park) and needs to be separated from the rest of the paved areas then the concrete sidewalk would be found on the CS-SWLK-CONC layer.

Just One Benefit

There are so many benefits to this formatting but let us look at just one often overlooked benefit – layer filtering.

In AutoCAD 2005, the Layer Properties Manager dialog box was revamped and the layer filtering tools were emphasized in this new layout. Yet, many of us (including me) still do not use them to the full. A layer filter is exactly that – a way to filter layers based upon properties.

To create a new filter click on the “New Property Filter” button in the top left of the layer properties manager dialog. A new layer filter properties dialog will pop up. Let’s create a demolition filter based upon the layer naming format we have established. Since demolition is a status of a group and is always found at the end of a layer, we can enter in the name section of the filter the “all” wildcard (*), the separator (the hyphen “-“), and then the demolition status field (“D”).

If you hit okay then the filter will show up in the left side of the layer properties manager and will be current only showing to you the demolition layers found in the drawing.

You can get even more specific than that. Say that there are two survey files being referenced in and you want to see only the topography layers for the field shot survey. We would add the “all” wildcard at the beginning since we do not know what the xref names are. Follow the wildcard with the pipe “|” that is used by AutoCAD to separate the xref name from the layer name. Then the “VF” discipline designator for field shot survey, the hyphen, and the “TOPO” major group. It should look like this “*|VF-TOPO”.

Conclusion

Some points for review:

1. EVERY layer in a drawing has a discipline designator and a major group just as every file has a name and a drive.
   • The discipline designator can be two characters – the major and minor designator.
2. Every layer shall be created in all caps. The reason is that since 2002, a smaller case layer name and an upper case layer name are TWO DIFFERENT layers. To avoid multiple copies of layers, confusion and to keep consistency, we put all layers in caps.
3. Be Consistent
4. EVERY group is EXACTLY FOUR CHARACTERS in length
5. Each group is separated from the other using a hyphen “-“
6. The status field ALWAYS goes at the end of the layer
7. Use common sense. I shouldn’t have to say it but just think about the life of the layer/project/drawing before you create the layer. This helps know what major group to place objects on especially when there are multiple groups the objects could belong to.

This layer naming system is used around the world. In fact, it is the layer naming format encouraged and built into the Autodesk software. No other CAD Standard (ISO or BS) is so widely accepted nor integrated into AutoCAD.

Now for the comments!