Map categories with an explicit dictionary
A small lookup list makes category changes reproducible and visible.
Write one mapping per line
Use the old value, a tab, and the new value, or write old => new. A tab is useful when values themselves contain the arrow. Preserve spaces deliberately: matching does not trim either side.
Check duplicate source keys
A source value can have only one replacement. Duplicate keys are rejected rather than letting the last line silently win. Optional case-insensitive matching can also make values such as READY and Ready collide.
Review values left unchanged
Unmapped cells are retained, not treated as errors. Compare the number of matching records with your expected categories and run a frequency summary first when the input vocabulary is unfamiliar.
Try this workflow: Value mapper. It loads a labelled fictional example that you can edit.