The title is "The Bride stripped bare by her bachelors even". It is also with some approximations the title of two previous works: "The bride stripped bare by the bachelors, 1912" and "The Bride stripped bare by her bachelors ,even, 1913".   

The subtitle is "Etant donné, 1.la chute d'eau, 2. le gaz d'éclairage". It is also with some approximations, the title of two later works: "Etant donnés le gaz d'éclairage et la chute d'eau, 1948-1949" and "l'Approximation démontable executée entre 1946 et 1966 à New-York" which is in Philadelphie.   

It is certainly fundamental that the subtitle of the Large Glass is the same as the one of this work in Philadelphie, that Duchamp only wanted to be shown after his death. This - if there were any left - does not leave any doubts as regards the logical connection between these 2 works. And it does not leave any doubts either as regards the importance of the subtitle.