It is unclear whether all regiments are covered. There is a suspicious absence of entries for cavalry regiments even though many Marsdens are known to have served in such units. Because of the British Army's commitments and involvements overseas, many of the births occurred outside England and so will not be found in either parish registers or UK civil registration. It is unclear to me at present whether registration in the regimental registers after 1837 was an alternative to civil registration or operated in parallel. If anyone knows the answer to this I will be pleased to hear from them.
Some births appear to be recorded more than once with different register references.
The reason for this is not known. Most of the table is straightforward and abbreviations used are listed below. Abbreviations RA - Royal Artillery Rfl. Surname Given Names Place Year Regt.