RFC 6241, "Network Configuration Protocol (NETCONF)", June 2011Source of RFC: netconf (ops)
Errata ID: 5401
Reported By: Rohit R Ranade
Date Reported: 2018-06-21
Section 8.9.1 says:
The XPath expression MUST return a node set. If it does not return a node set, the operation fails with an "invalid-value" error.
It should say:
The XPath expression MUST return a node set. If it does not return a node set, the operation fails with an <error-tag> value of "invalid-value".
It is unclear what is the meaning of "invalid-value" "error". Since the xpath will be part of "select" attribute, we can assume that a server can return a "bad-attribute" error-tag and having error-message indicating invalid-value for the attribute. This clarifies the <error-tag> to be used in such cases.
In other places, where error-tag has been mentioned, it is clear that "invalid-value" <error-tag> must be used.