046 Subfield $z - Public note:

Subfield $z contains a note relating to the date(s) recorded in the field.  The note is written in a form that is adequate or intended for public display.  It is not intended to substitute for system programming that correctly parses the date information itself for display purposes.

Examples:

046  ##  $k2008$2edtf$zCreation date

046  ##  $k2015$2edtf$zRelease date