20th century type is where I started seriously collecting coins. Your post hit a nostalgic warm spot in my heart.
Well done. If you want to get REALLY picky about your type set, take into consideration the 3 varieties of Standing Liberty Quarters: -- Variety 1 - No Stars Below Eagle (1916-1917) -- Variety 2 - Stars Below Eagle/Pedestal Date (1917-1924) -- Variety 2 - Stars Below Eagle/Recessed Date (1925-1930) And of course there are the Peace Dollars: -- High Relief (1921) -- Normal Relief (1922-1935) That sort of thing all depends on how particular you want to be.
I sort of suspected this was the case. Fortunately type sets can conform to whatever definition you want. If you look at the NGC Registry Type Set you'll see all three types. That's their definition.