In line with the Market Design for these processes, this Discussion Request relates to validation of
Market Messages to ensure that the inbound message rejects if MM received for Group Unmetered sites
– GMPRNs or TMPRNs
• Change of Legal Entity- 016 resulting in a 116R
• Meter Works-017 resulting in a 117R
• Meter Point Registration-010 resulting in a 102R
These Rejection Messages will be triggered where the Meter Point Type is equal to a Grouped MPRN or
Technical MPRN with a reject reason ‘IMP’ – Invalid MPRN (an existing code). This is to indicate the
request cannot take place due to the meter point being Grouped MPRN or Technical MPRN.

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