I don't know if there was one or not. However, if there is one it might be in Napoleon's Correspondence.

All cavalry regiments were ordered to have a 5th Squadron in 1806 which would be stationed at the regiments' depot and would serve as a replacement depot as well as train recruits and remounts. The regiments' majors would be in command and the squadron had to be ready for active service if required. The 5th Squadrons for all cuirassier and carabinier units was soon taken away/abolished, but light cavalry regiments organized up to eight squadrons per regiment as Napoleon preferred to organize new squadrons to existing regiments than organize new regiments.