Optional
lookupAn array of field ids on the parent table that will become lookup fields on the child table.
The relationship id. This is the field id of the reference field on the child table.
Optional
summaryAn array of objects, each representing a configuration of one field from the child table, that will become summary fields on the parent table. When you specify the 'COUNT' accumulation type, you have to specify 0 as the summaryFid (or not set it in the request). 'DISTINCT-COUNT' requires that summaryFid be set to an actual fid.
The unique identifier (dbid) of the table. This will be the child table.