Asset Index — Classification Breakdown Structure (CBS)

The Classification Breakdown Structure (CBS) categorizes digital twin assets according to industry-standard or custom classification taxonomies (for example: Uniclass 2015, OmniClass Table 23, COBie, or project-specific classification systems).

CBS tree navigation enables information managers and cost consultants to inspect elements grouped by classification code depth (e.g., 23.80 Electric Power → 23.80.70 Lighting → 23.80.70.11 Luminaires → Downlights).

Supported Classification Taxonomies

The CBS engine natively supports the following classification standards:

Classification Standard Code Format Example Section Delimiter Sample Code Pattern
Uniclass 2015 Pr_60_65_21_22 Underscore (_) ^[A-Za-z]{2}_\d{2}(_\d{2}){1,5}$
OmniClass Table 23 23.80.70.11.14 Dot (.) ^[0-9]{2}(\.[0-9]{2}){1,5}$
COBie Classification 23.80.70.11 Dot (.) Standard COBie category codes
Custom Taxonomy User-defined Dot (.) or Underscore (_) Custom regex string

CBS Taxonomy Configuration

Configuring CBS Parameters

In Section 4 of the Unified Asset Configuration Builder:

1. Classification Standard

Select Uniclass 2015, OmniClass Table 23, or COBie. Selecting a standard automatically configures the recommended 2-Digit Section Delimiter and Code Validation Regex Pattern. You may see other configurations which are enabled for specific projects. If the current configurations do not meet your specific requests then raise a feature request. Currently configurations are not user configurable.

2. Section Delimiter

Defines how taxonomy levels are parsed into tree depth:

3. Target Aspect Class & Properties

ECSQL Classification Strategies

The CBS engine utilizes three alternative ECSQL extraction strategies depending on how classification data is modeled in your iModel schema:

Strategy 1: Aspect Class Join (Recommended)

Joins the target aspect class with bis.Element to retrieve classification codes and asset labels:

SELECT aspect.Element.Id AS elementId, 
       aspect.ifcAssetClass AS classificationCode, 
       aspect.ifcuaid AS label, 
       ec_classname(e.ECClassId) AS className 
FROM IFCDynamic.ifcAspect_PSET_HS2_Parameters AS aspect 
JOIN bis.Element e ON e.ECInstanceId = aspect.Element.Id 
WHERE aspect.ifcAssetClass IS NOT NULL

Strategy 2: ElementMultiAspect JSON Extraction ($->property)

Extracts classification properties stored as dynamic JSON metadata within bis.ElementMultiAspect:

SELECT aspect.id AS elementId, 
       classificationCode, 
       aspect.ifcuaid AS label, 
       ec_classname(e.ECClassId) AS className 
FROM (
  SELECT $->ifcAssetClass AS classificationCode, 
         $->ifcuaid AS label, 
         Element.Id AS id 
  FROM bis.ElementMultiAspect
) AS aspect 
JOIN bis.Element e ON e.ECInstanceId = aspect.id 
WHERE aspect.classificationCode IS NOT NULL

Strategy 3: Direct Element Property Query

Queries classification code properties directly from bis.Element:

SELECT e.ECInstanceId AS elementId, 
       e.ifcAssetClass AS classificationCode, 
       e.UserLabel AS label, 
       ec_classname(e.ECClassId) AS className 
FROM bis.Element e 
WHERE e.ifcAssetClass IS NOT NULL

Code Parsing and Taxonomy Tree Construction

During harvesting, raw classification strings are validated and expanded into a multi-tiered taxonomy tree:

  1. Format Validation: Codes are checked against the regex pattern. Invalid or non-conforming strings (e.g. TBC, N/A, TEMP) are filtered out and registered as validation issues.
  2. 2-Digit Parsing: The code is split using the section delimiter into 2-digit pairs.
  3. Node Hierarchy:
    • 23 — Electric Power and Lighting (Group Level)
    • 23.80 — Electric Power (Sub-Group Level)
    • 23.80.70 — Lighting (Section Level)
    • 23.80.70.11 — Luminaires for Internal Lighting (Object Level)
  4. Asset Attachment: Elements are attached as leaf nodes under their exact classification code section.

CBS Taxonomy Tree View

Troubleshooting

Symptom Cause / Remedy
CBS tree is empty The targetAspectClass or propertyNames specified in configuration do not match the iModel aspect schema. Use the iModel Console to inspect aspect class properties.
Classification codes appear under [Unclassified Assets] Elements lack classification values, or codes failed regex validation (e.g. Pr-60-65 using hyphens instead of underscores).
Uniclass codes fail to expand hierarchy Verify that the Section Delimiter is set to _ (Underscore) for Uniclass 2015.

Related Documentation