1) Looking through V2.0 of the Properties of Comet Nuclei dataset, I noticed that some products have the values in the DISCOVERY_ID columns sandwiched between parentheses (e.g., colors.tab) and other products do not (e.g., albedos.tab).  Should we not be consistent across the data products in at least that dataset?

2) Add (or subtract) all of the DISCOVERY_IDs for each table, being consistant for all tables.