I'm trying to look at tables from the SF1 and I've noticed they don't seem to follow a consistent format. The ACS ID consistently use tableID-underscore-variable number. For SF1 variables I was under the impression that it worked similarly, because in the examples, the query for total population (for which the table ID is 'P001') uses the ID 'P0010001' or what I thought was Table P001 plus cell ID 0001. However I'm trying to use the table 'PCT20' (Residents in group quarters) and I can't figure out the proper suffix to use to retrieve each individual cell. Adding 001 or 0001 for the cell ID to the end just returns errors.