From Valve Developer Community
1: Starts Open- Obsolete. Door behaves more like the doors in Half-Life. Some outputs don't work.
- 4: Non-solid to Player - Sets the collision group to
COLLISION_GROUP_PASSABLE_DOOR, so the player cannot collide with it while other things can. This is not compatible with Ignore Debris as that also sets a collision group.
- 8: Passable - This door is solid to nothing at all.
- 32: Toggle - Inputs are interpreted as to change between open and shut. That is, inputs are interpreted as to open if the door is closed and to close if open, instead of the default behavior where inputs are always interpreted as to open. This overrides the delay before reset (wait) to -1 i.e. never reset.
- 512: NPCs Can't - NPCs can't open this door.
- 1024: Touch Opens - When a player or NPC touches the door, it will count as an attempt to open it.
- 2048: Starts locked - This door spawns locked and cannot be opened by the player or NPCs (but buttons can still trigger it)
- 4096: Door Silent - This door makes no noise.
- 65536: New
Userules !FGD - To do: Describe difference..?