[klop]

I want to know what (1 << 20) means...
Why they didnt write the flags like this?

// DF_NO_HEALTH 1
// DF_NO_POWERUPS 2
// DF_WEAPONS_STAY 4
// DF_NO_FALLING 8
// DF_INSTANT_ITEMS 16
// DF_SAME_LEVEL 32
// DF_NO_ARMOR 2048
// DF_INFINITE_AMMO 16384
// DF_NO_FOOTSTEPS 131072
// DF_ALLOW_LEAN 262144
// DF_OLD_SNIPERRIFLE 524288
// DF_GERMAN_SHOTGUN 1048576