The nt:versionLabels node type has the following definition (repeated from 6.7.22.14 nt:versionLabels):
NodeTypeName
nt:versionLabels
Supertypes
nt:base
IsMixin
false
HasOrderableChildNodes
false
PrimaryItemName
null
PropertyDefinition
Name *
RequiredType REFERENCE
ValueConstraints ["nt:version"]
DefaultValues null
AutoCreated false
Mandatory false
OnParentVersion ABORT
Protected true
Multiple false