This property is read-only..

Subset of a part with information about the unit. At parts for cables, connections and their accessories (for example shrink tubes or insulating tubes) the contents of this property is evaluated as a length and the entry of decimal values is possible, for example "0.7 m". The full value with all decimal places is always stored; the value is not rounded up. This ensures precision is retained when converting to a different unit. This property may be used in bills of materials, for example.

Reference

ArticleReferencePropertyList Class
ArticleReferencePropertyList Members