Autodesk 24000-000000-9860 - Revit Architecture - PC User Manual page 263

You can also replace a dimension value with variations within a class of element, as shown below.
You cannot replace a permanent dimension value with a numeric value. You will receive a message if you
attempt to do so.
To replace permanent dimension values with text:
1 In the drawing area, select the dimension you want to edit.
2 Click the dimension value.
The Dimension Text dialog displays.
3 In the Dimension Value field, select Replace With Text.
4 In the text box, enter the text you want to display in place of the dimension value.
5 Optionally, enter text in the Above and/or Below text fields.
6 Click Apply.
7 Click OK.
Permanent Dimensions | 225