This is used as a quick way of retrieving a piece of data, but bypassing the read if the data has not changed since the last read.
Call the service passing it a node version reference for the node, one for the member type, and optionally a timestamp when it was last retrieved or updated.
If the data has changed since the timestamp, the service will return changed of true, timestamp set to the derivation timestamp of the node, and the node member value.
If the data has not changed since the timestamp, the service will return changed of false and the derivation timestamp.
If a member type is not passed, the service will return the changed and timestamp elements but not the value.
<password>password</password> <nodeVersionReference/> <nodeVersionReferenceMemberType/> <timestamp/>
<errorNumber>0</errorNumber> <changed>true|false</changed> <timestamp/> <value/>
102 - Not found
103 - Parameter error