Each resource is bounded to a time span, whatever type of event it refers to (e.g. creation, production, publication or modification, acquisition). When you describe your resource, it is thus highly recommended to provide any chronological indication of its life cycle.
Note: This field should not express a date associated with the intellectual content of the resource. If you refer to this type of information, use instead the Temporal coverage field.
Phaidra Editor provides you with many types of dates that you can choose from:

Date:
A point or period of time associated with an event in the lifecycle of the resource.
Date created:
Date of creation of the resource.
Date modified:
Date on which the resource was changed.
Date available:
Date (often a range) that the resource became or will become available.
Date issued:
Date of formal issuance (e.g. publication) of the resource
Date valid:
Date (often a range) of validity of a resource.
Date accepted :
Date of acceptance of the resource.
Date copyrighted:
Date of copyright.
Date submitted:
Date of submission of the resource.
Date of production:
Date of the inscription, fabrication, construction, etc., of an unpublished resource.
Date accessioned:
Date on which an identification number was assigned to a particular donation or acquisition of the analogue object.

If you need more than one type of date, duplicate the field.