An electrical designer wants to add a parameter to a lighting fixture schedule without editing the families. Which parameter type should the designer use?

A Project Parameter is the correct type to use when adding information to a schedule for a category of elements, like lighting fixtures, without modifying the family files. The designer can create a new project parameter (e.g., "Lamp Type"), assign it to the "Lighting Fixtures" category, and then add it as a field (column) in the lighting fixture schedule. This parameter exists within the project file and can be populated for each fixture instance directly in the schedule or properties palette.

A. "Schedule parameter" is not a formal Revit parameter type. While you can create calculated parameters within a schedule, a project parameter is used to add new data fields.
C. A global parameter is used to drive dimensions and constraints; it cannot be assigned to an element category and added to a schedule as a data field.
D. A family parameter would require editing each lighting fixture family, which the question explicitly states the designer wants to avoid.

1. Autodesk Revit Help. (2023). Add a Parameter to a Schedule. "You can add any project or shared parameter to a schedule... If the desired parameter is not listed, you can click Add Parameter to create a new project parameter."

2. Autodesk Revit Help. (2023). About Parameters in Schedules. "Project parameters can be added to any element in a project. They exist only in the project file in which they were created... You can use project parameters in single-category or multi-category schedules."

3. Syracuse University, School of Architecture. (n.d.). Revit Parameters. "Project Parameters are created within a project file and can be assigned to any category of element. They are useful for creating schedules and sorting/filtering information that is specific to the project."