About Lookup Tables

Lookup tables are used to define parameter values in an external comma-separated values (CSV) file.

This lets you specify multiple part sizes that are based on a table without creating a separate family type for each size. Revit provides a size_lookup function that can be used to read the necessary values from a CSV file.

Data from lookup tables for is stored within the family and use the size_lookup function. See Managing Lookup Tables. For upgraded projects, you can define the location of lookup table files with the LookupTableLocation parameter in the Revit.ini file. Folders are created for each type of content installed.

Note: The Revit.ini file is located in this folder: %APPDATA%\Autodesk\Revit\<product name and release>

Lookup tables are used in conjunction with type catalogs. For information about creating type catalogs, see Creating a Type Catalog.

The syntax for the size_lookup function uses the following format:

result=size_lookup(LookupTableName, LookupColumn, DefaultIfNotFound, LookupValue1, LookupValue2, ..., LookupValueN)

Where:	Is:
result	the returned value.
LookupTableName	the name of the CSV file to lookup.
LookupColumn	the name of the column from which the result value is to be returned.
DefaultIfNotFound	the value that will be returned if LookupValue is not found.
LookupValue(1-N)	the value to find in the first, second, and subsequent columns of the table. (When looking up values, the first column is skipped.)

Notes:

• The size_lookup function provides the ability to look up numerical values only.
• The size_lookup function is intended for instance parameters. If you want to use tabular data to define types with unique values for each type, see Creating a Type Catalog.