"Has improper value for" is a predefined property to track input errors for irregular value annotations that was likely caused by type or allowed value restrictions.
"Has subobject" is a predefined property representing a container construct that allows to accumulate property-value assignments similar to that of a normal wiki page.
en:The language of the element contained in the representation. This is a mandatory attribute. The value UND (undefined) should be used if the language cannot be set for some reason. However, use of UND is discouraged by the W3 consortium. +
The language of the element contained in the representation. This is a mandatory attribute. The value UND (undefined) should be used if the language cannot be set for some reason. However, use of UND is discouraged by the W3 consortium. +
