A Comma Separated Values (CSV) file stores tabular data in plain text.
- The first row of values in the CSV file is for header information, to describe the contents of subsequent columns.
- The headers are of the format ParameterName##ParameterType##ParameterUnits
- Acceptable parameter types are: NUMBER, LENGTH, AREA, VOLUME, ANGLE, and OTHER.
- For example, a column may have the following header: TotalArea##AREA##INCHES to represent the total area in square inches.
- For example, a number must have the following header: param_name##NUMBER##GENERAL or param_name##NUMBER##PERCENTAGE.
- The first column in the CSV file contains a description to identify the row that is being edited. The Lookup Function ignores the first column and the values are looked up strictly on the column order, starting in the second column.
- When looking up values, Revit ignores the parameter names and the column headings.
Following is a sample Excel table used to create a CSV file:

The table above creates a CSV. It will look like this when opened in Notepad.
,ND1##length##inches,ND2##length##inches,ND3##length##inches,SED##length##inches
1.5,1.5,-1,-1,1.915
2x1.5x1.5,2,1.5,1.5,2.39
2x1.5x2,2,1.5,2,2.39
2x2x1.5,2,2,1.5,2.39
3x3x1.5,3,3,1.5,3.52
3x3x2,3,3,2,3.52
4x4x1.5,4,4,1.5,4.52
4x4x2,4,4,2,4.52
4x4x3,4,4,3,4.52
6x6x4,6,6,4,6.647