Do we need any text to give guidance to valid times when an Indicator is revoked

[rpiazza]

Indicators have valid_from/valid_until properties which are meaningless if the Indicator is revoked.

In CACAO they had the following text.

If the revoked property is true then this property MUST be ignored.

Do we need this in STIX?

[rpiazza]

Once an object is revoked, it is invalid, so it makes sense to ignore the valid_from/valid_until properties.