Contains an opaque string representing a specific instance
of a datastore or data resource. A client can use this
string for equality comparisons between yang-entity-tag
values.
If any configuration data node values changes, or the
relative order of any user-ordered data changes, then
the server MUST change the entity tag value for the
running datastore to a different value. If the server
maintains entity-tag values for configuration data nodes,
then the server MUST change the yang-entity-tag value for
any affected data node.
Only yang-entity-tag values for the same target resource
instance can be compared. Only the 'strong entity tag'
form is required. A server MAY support the 'weak
entity tag' form. If so, then 2 YANG data node resource
instances are considered to be equivalent if they
contain the same value subtrees and all user-ordered
data nodes share the same relative order.