The data definition for the Generator Unit ID field was baselined in the Retail Market Design at version
6.0, as detailed within MCR 120, as part of the suite of changes to satisfy new requirements of SEM
implementation.
The draft XML schema issued on the 1st of March includes provision for a pattern validation to match the
new SEM Participant GUID format of GU_nnnnnn.
As the GUID field will be used to contain both Pre-SEM Participant Generator Unit ID 3 digit values and
also 4 digit Export Arrangement IDs for Non Participant Generator sites it is proposed that this pattern
validation is removed. The field will remain as a 9 long field in the XML, this will allow this field to be
populated in xml with anything from 0 to 9 characters.
Note: the data definition within the Market Design will remain as is.

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