"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.
en:The date of the begin of the exsistence of the agent, e.g. the birthday of a person or the founding of an institution, calculated from ValidFromDay, - Month and -Year +
The date of the begin of the exsistence of the agent, e.g. the birthday of a person or the founding of an institution, calculated from ValidFromDay, - Month and -Year +
