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README.md

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+# WRL projects team costing tool
+
+This spreadsheet is used to estimate the costs when preparing proposals for the WRL projects team.
+
+## Workflow
+
+`xlsx` is a binary format, and is not well-suited for version control.
+
+When making changes to the macro modules within the workbook, please ensure the changes are mirrored in the vbs text files (e.g. `costing-tool-module-1.vbs`) before each commit. This makes it much easier to view the changes using `git diff`.