You can find the full list in the source too. Look in src/inptport.c, lines 426-928 (as of mame 0.111u1), for the universal defaults, but you need to look at src/windows/input.c in the osd_customize_inputport_list() function, lines 2280-2348, for the windows specific changes on top of the universal defaults.
The defaults have had minor changes a couple times the past few versions, and might have a couple more in the not too distant future. Official windows mame uses almost 450 different inputs, if you include players 5-8, mahjong, UI, mess related, and other "not common" inputs.
Attatched is a tab delimited list as of mame0.111u1.