From the Autodesk App Store:
The Amplify Grid Prefix | Suffix add-in is a helpful tool for adding a prefix or suffix to grids labels within a project file.
The add-in prompts the user to choose what prefix or suffix to append to the grid label, and whether to change all grids in the project or only a selection of them. This can be used to add an indicator to the grid label such as (E) for “existing” on a phased project, or as a method to organize grid labels on large/complex models…
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