"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:Year of the publication date (primary date). Only numbers are allowed and the year must be entered with 4 digits ('1998', not '98'). //[RefMan 05: Y1,PY pro parte] +
Year of the publication date (primary date). Only numbers are allowed and the year must be entered with 4 digits ('1998', not '98'). //[RefMan 05: Y1,PY pro parte] +
