preferred_name: A proper value is applicable but not known (e.g., date of 1st contact is unknown)
preferred_name_lc: a proper value is applicable but not known (e.g., date of 1st contact is unknown)
label: A proper value is applicable but not known (e.g., date of 1st contact is unknown)
label_lc: a proper value is applicable but not known (e.g., date of 1st contact is unknown)