data for this element must be Recorded as instructed: the data must be appropriate for the resource, even if it is not entered exactly as instructed due to interpretation or error
data for this element is CoreIf: if the data has not been given as another element instead:
it is ok if the element is missing, as long as the related element is present or if the specific circumstances allow it to be skipped; but
it is not ok:
if the element is missing and the related element is also missing or if the specific circumstance do not allow it to be skipped (except for error or old cataloging rules); or
if you feel that the fact that the element is missing indicates a true difference
but be sure to check the resource carefully, if the data for the element is Core, or if the data is important for differentiating the resource from a similar resource
Check below, for any useful Notes
Matching Notes
Make allowances for minor differences in how this data might be recorded, especially in non-RDA records