-S.06.02.02 does not exits because the anual code S.06.02.01 is reused for the quarterly reporting. Note that there are not changes in comparison with anual table structure.
-S.06.02.03 does not exits for day 1. Note that this last ".03" means Day 1 Solo.
The idea of the codification is to reuse (when possible) the same codes as far as the table structure is the same. This helps to easily see the commonalities or to highlight that there are differences in the templates without needing to compare the business logs. Also it may also help on the database mappings and to reduce the number of worksheets.
You can find more information here in point IV.3.2.1 and here at the bottom of page 5. The entry points matrix available in the EIOPA reporting formats page helps to see how the logic is been applied.