"Significant" independent films

I'd be interested to know what criteria they used - "significant" is a pretty broad word. Do they mean the movies made money (which is what this looks like) or that they had a cultural impact or something else? Some great movies on this list, and I'm happy to notice that I've seen almost all of these. I basically only missed one per decade - The Toxic Avenger, Braveheart, Trainspotting, Inglourious Basterds.

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The Independent Film and Television Association is marking its 30th anniversary by selecting the 30 Most Significant Independent Films from around the world produced in the past 30 years:

1981-1990: Amadeus; Blue Velvet; Dances With Wolves; Das Boot (The Boat); Gandhi; My Left Foot; A Nightmare on Elm Street; Platoon; sex, lies and videotape; The Terminator (Honorary mentions: The Killing Fields; The Last Emperor; The Toxic Avenger)

1991-2000: Braveheart; Crouching Tiger, Hidden Dragon; Fargo; Four Weddings and a Funeral; Life is Beautiful; Pulp Fiction; Reservoir Dogs; The Silence of the Lambs; The Usual Suspects; Where the Day Takes You (Honorary mentions: Basic Instinct, Good Will Hunting, Trainspotting)

2001-2010: Brokeback Mountain; Crash; The Hurt Locker; Inglourious Basterds; Juno; Lord of the Rings: Fellowship of the Ring; Million Dollar Baby; Monster; The Pianist; Slumdog Millionaire; (Honorary mentions: Bowling for Columbine; Memento; Twilight)