You can use the Classify projects in batch run [Batch classification of projects] plugin ( "Customize order number and type code " plugin in older versions) to successively assign the desired variable to all projects for a selected class characteristic.

Select a variable. The plugin goes through the entire structure and at projects containing the variable, the classification will be assigned.

Afterwards a listing shows at which projects the assignment was successful and at which not. Now you can use another variable for the assignment as long as all projects are classified.

You can find details on this under Section 5.12.6, “ Batch classification of projects ”.