This flag explains why there is no appropriate value in the corresponding date field, Date of Last Cancer (tumor) Status [1772]. This data item is required for CoC-accredited facilities as of cases diagnosed 01/01/2018 and later.

This information is used for patient follow-up and outcomes studies. As part of an initiative to standardize date fields, date flag fields were introduced to accommodate non-date information that had previously been transmitted in date fields.

12	A proper value is applicable but not known. This event occurred, but the date is unknown (that is, the Date of Last Cancer (tumor) Status is unknown).
Blank	A valid date value is provided in item Date of Last Cancer (tumor) Status [1772].