Message

The Request Identifier value MUST be expressed in a UUID syntax (RFC 4122).

Context
query:QueryResponse
Test
matches(normalize-space(./@requestId), '^[0-9a-fA-F]{8}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{12}$')
Usage
/ query:QueryResponse