What is the ordering of Deuterium and Tritium in the isotopic layer?
The ordering of isotopes goes in descending atomic mass. Thus the ordering for Tritium, Deuterium and Protium is T>D>1H. Note that if you specify the generic H (rather than the specific protium isotope 1H) then it will obviously not appear in the isotopic layer (which only deals with specific isotopic enrichment).