CAD layer naming standards, compared field by field

A layer naming standard is an agreement on how every layer is named so that a wall reads as a wall in any file, from any office, on any project. Three frameworks dominate. North America runs on AIA/NCS. Europe and international work runs on ISO 13567. The UK adds an information-management layer through the BS 1192 lineage, now ISO 19650, with Uniclass underneath. They overlap in intent and diverge in syntax, and the one you adopt is usually decided by where your clients are and what their contracts demand.

AIA CAD Layer Guidelines / US National CAD Standard (NCS)

The dominant North American framework. Layer names are human-readable, hyphen-separated fields in a fixed order: Discipline Designator, Major Group, optional Minor Group (up to two), optional Status.

• Discipline Designator - two characters. A architectural, S structural, M mechanical, E electrical, P plumbing. A second character refines it: AD demolition, AI interiors.
• Major Group - four characters, the building system. WALL, DOOR, GLAZ.
• Minor Group - four characters, optional, narrows the major group. A second minor group narrows it again.
• Status - one character, optional. N new, E existing, D demolish.

A fully qualified name reads A-WALL-FULL-N: architectural, wall, full-height, new. Add a second minor group and it becomes A-WALL-FULL-DIMS-N - the dimensions on full-height walls.

The AIA CAD Layer Guidelines are bundled into NCS v6 alongside the Uniform Drawing System and AEC graphic standards, published by the National Institute of Building Sciences. NCS is mandated on US federal work - the GSA, the Department of Defense, and the US Army Corps of Engineers all require it - which makes it non-negotiable for any firm chasing government contracts. Most US-trained drafters already read it without a code table.

ISO 13567

The international standard (ISO 13567-1 and -2:2017) for organizing CAD layers. Where NCS spells systems out in words, ISO 13567 encodes them. A layer name is a continuous alphanumeric string of fixed-length fields - three mandatory, the rest optional.

• Agent Responsible - two characters. The party that owns the layer: architect, structural engineer, services.
• Element - six characters. The functional part of the construction, drawn from a national classification table - Uniclass in the UK, CI/SfB historically.
• Presentation - two characters. How the information is drawn: linework, text, dimensions, hatching.
• Optional fields follow in a defined order - Status, Sector, Phase, Projection, Scale, Work Package - each a fixed width so a parser can slice the string without delimiters.

A name like A-374-G reads agent (architect), element (the classification code for a roof window), presentation (graphics). The codes are short, which keeps names compact, and unreadable to anyone without the reference table - which is the cost of the design.

ISO 13567 is adopted nationally with local annexes: NF EN ISO 13567 in France, DIN EN ISO 13567 in Germany, BS EN ISO 13567 in the UK. It is the lingua franca for EU collaboration and is frequently required on European public-sector and cross-border projects. Because element codes map onto building classification systems, it ties cleanly into BIM workflows.

BS 1192 / ISO 19650 + Uniclass 2015

The UK framework, and less a layer syntax than an information-management discipline wrapped around one. BS 1192:2007 set out file container naming and Uniclass-based classification. The BS EN ISO 19650 series has since superseded it for information management; the UK National Annex defers actual layer naming to BS EN ISO 13567-2 and mandates Uniclass 2015 as the classification system, now carried as metadata rather than baked into every layer name.

• Container naming - structured file and container identifiers, project-field by project-field.
• Layer naming - handled by ISO 13567-2, so the field structure above applies.
• Uniclass 2015 - the mandatory classification, a stable shared vocabulary supplying the element codes and the metadata that links a layer to the wider model.

This is the BIM-pressure layer. Under ISO 19650, clean and classified layers stop being tidiness and become a contractual deliverable - a precondition for IFC export, model federation, and clash detection. A misclassified layer breaks the downstream coordination chain. The framework is heavy and document-led, and it says nothing about how to remediate files that arrive non-compliant. That responsibility lands on the drafter.

The three standards side by side

What a standard does not give you

Every framework above defines the destination. None of them moves your files there. A standard specifies that an architectural full-height wall is named A-WALL-FULL-N; it gives you no mechanism to take a consultant's MURI, a contractor's A-WALL-FULL, or a legacy WALL_EXT and conform it. That work lands on a human, layer by layer.

Converting non-compliant incoming files to the target is what MorphoCAD does. Pick the standard you map to - AIA/NCS, ISO 13567, or a custom template from one of your own drawings - run MORPHO, and it reads each layer in a received DWG by meaning and proposes the matching target. You review every row, scored for confidence, and nothing changes until you click Apply. The standard tells you what the names should be; MorphoCAD gets messy drawings into them.

FAQ

Which standard should we adopt? Let the work decide. Architecture and engineering offices serving US clients adopt AIA/NCS because federal contracts require it. Offices on European or cross-border projects adopt ISO 13567. UK firms under BIM mandates inherit ISO 19650, which points layer naming at ISO 13567-2 and adds Uniclass. Most offices build a house standard on top of whichever applies and tune it to their disciplines.

Are AIA/NCS and ISO 13567 compatible? Conceptually, yes - NCS was designed to align with ISO 13567, and the NCS status field exists partly for that conformance. But the syntaxes differ: NCS is readable words separated by hyphens, ISO 13567 is fixed-width codes with no delimiters. A name does not translate from one to the other by reformatting; the fields carry different information.

Is BS 1192 still current? For information management, no - the ISO 19650 series superseded it. The naming and classification ideas live on: the UK National Annex routes layer naming to BS EN ISO 13567-2 and keeps Uniclass 2015 as the mandatory classification.

Do I have to buy the standard to use it? The published documents - NCS via the National Institute of Building Sciences, ISO 13567 via ISO and its national bodies, the BSI standards - are paid. The naming rules and field structures are widely summarized for free, and Uniclass tables are free from NBS.

Why are ISO 13567 layer names so hard to read? By design. Short codes keep names compact and language-independent, at the cost of being unreadable without the reference table. A-374-G means nothing by eye and everything to a parser - exactly the kind of name that is slow to map by hand.

Does adopting a standard make our drawings compliant? No. A standard defines compliance; it does not produce it. Every layer still has to be named correctly, and every incoming file from an outside party still arrives in someone else's convention. Enforcement is a separate problem from definition.