Complex sentence: These sub-squares are 5 minutes by 2.5 minutes, though the 6 digit form is not always used though the more precise form is required in the AARL's 10 GHz contest.
Split into simpler sentences: These sub-squares are 5 minutes by 2.5 minutes. This 6 character form is not always used, though it is required in the AARL's 10 GHz contest.