013 Subfield $d - Date:

Subfield $d contains a date, usually assigned by a competent authority (typically a patent office), reflecting when a patent or similar certificate was granted or upon acceptance of an application for such a grant by that authority. The date of an application is typically the date of receipt by the agency. Other dates, such as effective dates, exhibitions dates, etc. are also recorded in this subfield. Multiple dates are recorded in separate occurrences of subfield $d if they all relate to the same patent document. Qualifying information is recorded in subfield $e (Status information) . The date is recorded according to Data elements and interchange formats - Information interchange - Representation of dates and times (ISO 8601). The date requires 8 numeric characters in the pattern yyyymmdd (4 for the year, 2 for the month, and 2 for the day).

Examples:

013 ##$a84-948$bnl$coktrooi$d19840326

013 ##$a70-123456$bxxu$cstatutory invention registration$d19700414 (granted)$d19710419$eeffective