validThrough and validUntil

Hello.

Do we need both

https://schema.org/validUntil 'The date when the item is no longer 
valid.' (used on Permit)

and

https://schema.org/validThrough 'The date after when the item is not 
valid. For example the end of an offer, salary period, or a period of 
opening hours.'

Phil.

-- 

Phil Barker <http://people.pjjk.net/phil>. http://people.pjjk.net/phil
PJJK Limited <https://www.pjjk.co.uk>: technology to enhance learning; 
information systems for education.
CETIS LLP <https://www.cetis.org.uk>: a cooperative consultancy for 
innovation in education technology.

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