Right click the label for the R-group you wish to edit in your specification text and select the Edit R-Group option from the context menu
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OR
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​Open the R-groups Manager, locate the entry for the desired R-group in the left-hand sidebar listing, and click the edit pencil icon that appears on hover.
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Make the desired changes in the dialog presented.
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Click the Save button.
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See Describe an R-group for description edits.