No Time field for plone.registry?

Is there a valid reason why there is no persistent Time field available, but all the other date related fields are?

zope.schema contains: Datetime, Date, Timedelta and Time]: zope.schema/_field.py at master · zopefoundation/zope.schema · GitHub

plone.registry contains: Datetime, Date and Timedelta: plone.registry/field.py at master · plone/plone.registry · GitHub