Layer naming and use standards

[colinawright]

Most CAD managers will agree that layer naming and use is perhaps THE most important but least well dealt with issue in CAD management. The following notes relate to a well-researched and thoroughly tested system that is sophisticated enough to cope with composite models that include multiple drawing types (general arrangement plan, electrical plan etc.) and multiple levels (level 01, level 02 etc.) all in the one coincident model and yet simple enough to suit the most basic of drawings. Although designed for architects it is readily adaptable to any profession and in fact makes provision for the combining of drawings from different professions.
ACADlayer is such a standard integrated into a much more extensive Autocad proprietary, third-party, custom tool set, ACADUI, consisting of ACADkeys, ACADlayers and ACADtools but the naming concepts are free to be used by anyone. The layer names produced by ACADlayers are compliant with yet simpler and more logical than would be generated by following ISO/DIS 13567.

ISO/DIS 13567 rules:
• It is intended to provide a universally applicable conceptual structure.
• Layer names are constructed of several fields, some of which are mandatory and others optional.
• Fields are designed to be exclusive, that is, only one type of data per field.
• The structure is to allow migration of data from pre-existing layer name systems.
• Overly complex structures are to be avoided. Syntax and data coding should be designed for easy interpretation and manipulation.
• The Standard defines: the concepts to be coded in each of the fields, the order of the fields, the field lengths and sometimes coding.
• The Standard allows for variation on a project by project basis provided the procedures used are documented in a way that allows future retrieval of the layer information.
• It is emphasized that the ISO default is a starting point for defining national or project standards and is provided as a neutral standard for archiving or data exchange.
• Provided that the Mandatory fields required by the Standard are always used, conceptual conformance permits Optional fields to be used in any order and length, though the conceptual content of each field can not vary from the definitions in ISO/DIS 13567.
• If a project layer system varies from the ISO default, documentation must be provided for the project specific system identifying and describing all valid values of all non-default fields.

ACADlayers concepts are best illustrated in the following dialogue-box:

PLEASE VIEW THE ATTACHED FILE - CADlayers.JPG

Layers are automatically generated by picking values from the seven fields, beginning from the left, to generate twelve-character-long names that automatically comply with naming rules and are automatically generated with the correct colour and linetype. The values in the fields can be customised to any discipline and the columns scroll to accommodate as many values as required. If a desired value is not found then by clicking on “other”; custom values can be inserted.
Looks too complicated? Perhaps; but this is an all-encompassing scheme for single-composite-models. If you have a simple single concept model then you can optionally use a five character naming system using just “object”, “pen” and “colour” or just not use the automated system at all. But whatever you do you should set some layer standards and stick to them. As one previous post under CAD management implies; there are three important things for CAD standards, they are: LAYERS, LAYERS and LAYERS.

CADlayers optionally allows the use of five-character names generated from the first three fields but you would not use the dialogue box for this. Also if you don’t like dialogue boxes then you can do what I by preference do, that is; do it all through keyboard. Five-character names are a breeze to create and manage but custom commands are required to provide efficient layer filtering for the twelve-character-names for viewing and plotting.

I believe that the lack of availability of such a program within Autocad has done much to limit the practical application of ISO/DIS 13567. If you are interested in further pursuing this topic, tell me what you think and I can provide more detail. If you think that it would be worth separating ACADlayers from ACADUI and making it available publicly let me know? There is no copyright restraint on using these recommendations.

PS: Can anyone tell me how to place an illustration within the text?

[cadtag]

I'm a bit confused -- are you advertising a product for sale, suggesting an ISO standard, or What?

[Wanderer]

I seem to recall having a somewhat similar conversation with Peter Jamtgaard a few years ago at AU.
You might want to search the programming forums to see if he's posted anything related...

[colinawright]

You're confused!! That's just a polite way of saying I talk too much and fail to get to the point. I'm not suggesting an ISO standard - I'm actually recommending it. Many CAD users haven't even heard of it let alone use it. The point of my post was to advocate the use of ISO/DIS 13567 and to show at least one way of making practical sense of it.
I used an example from a layer management program that I wrote for myself - a method that I have used for twenty years very successfully (for architects at least).
It incorporates standards for layer naming, line weights and colour/line relationships and methods of filtering layers for viewing and plotting. On the other hand layer names can be very short (five characters) for simple drawings yet still following ISO/DIS. I am now retired and don't want to waste all that thinking.
With a bit of time and effort I could separate it from its host program. That's if anyone is interested. Thanks for your response.

[cadtag]

If it's an object-based standard, as seems to be indicated by the graphic, then I'm not going to be interested. My preference is a 'systems' based approach for layer naming. It lends itself better IMO to a broad spectrum of AEC work (No opinion about widget/mgfing needs)

I've used both schemes, and object-based stuff just doesn't work all that well with civil, process, or mechanical. YMMV

[KCM]

I've referred to ISO13567 and used it, along with the AEC conventions in creating layer naming systems. It is nice that it is comprehensive in the object elements it covers, but it isn't the most immediately intuitive and as cadtag said, it isn't universally applicable. It is also a bit creeky these days, developed for when screen space was a premium and character limits were tight, hence all of the codes.

Cheers for bringing it to our attention though.

[colinawright]

CADtag thanks for your comments. Can you tell me a little about "SYSTEMS" based approach? This is entirely new to me. I would like to understand.

[colinawright]

CADtab and KCM - thanks for your input. Will you expand a bit on your comments please? Some examples would help to understand your preferences.

[cadtag]

Systems approach to layer naming using NCS;

Most of my work is Civil these dayss, with a smattering of wtp/wwtp projects. For these areas, thinking in terms of the system is helpful, and usable. Taking a wastewater treatment plant as an example, we've got pipes, tanks, pumps, valves, etc. All the objects are the same, but they are all part of separate systems. No one wants to connect a finished water line to a effluent liquor pump...... so using NCS style names and grouping by system as Major Groups helps to maintain consistency.

For instance,, Discipline code for Process work is "D", and the Major Group for 'Waste Activated Sludge" would be 'WASP". Piping would then fall into D-WASP-PIPE, Fittings to D-WASP-FITT, valves, etc all follow a similar pattern. It's easy and straightforward to isolate individual systems and ensure that they are complete,not interconnected, and go where they need to go. The basic scheme is always Discipline-System-Object-Modifers.

Works reasonably well in Civil as well, C-TOPO would be the discipline & system for topographic data, contours, etc. C-STRM can collect everything related to stormwater infrastructure and make sure it's separate from C-SSWR so the sanitary blackwater does not mix into the stormwater. C-WATR, C-REUS, C-IRR, etc keep all the different water types from interacting.

And of course, the NCS was primarily designed by architects for architects, so there's a lot of capability there for buildings and building systems.

[colinawright]

CADtag, thanks for your explanation of a systems based approach to layer naming. It makes absolute sense in the environment you work in. The difference in the example I gave is that: The Object field is much simpler (three characters only) as architectural drawings do not normally require that level of detail but if say piping was to be shown on an architectural plan it would probably be an attachment from an external consultant and thus retain the layers generated by the consultant whilst acquiring a Block or Attachment reference layer from the example host system. Such a layer might have the object code "PIP". This aspect of the Object code is unfortunately off-screen in the screen-shot provided.

Since the additional fields in the example system would still apply, the resulting layer names would provide the opportunity to control visibility of piping objects as a whole by using its reference layer or individually by their original layer names (as modified by the XREF process).

The ISO Standard also provides for Agent and Status fields that might be useful as prefixes to the layer names. Not that I would recommend this. Regards, Colin