Given the currently available commands, you could think of a subtable as just a named table, yes. We did consider calling that parameter "-name" and presenting them exactly as named tables, in fact. However, the way they are implemented is much closer to the presentation you see here: all of the data in a subtable is actually present as part of the main table. This may matter in the future as more features are added (for example, we may someday support nested subtables), so it was decided to present the functionality as "subtables".