Types/EntityPrototypeFlags
"placeable-[force]"
- "placeable-player"
- "placeable-neutral"
- "placeable-enemy"
placeable neutral/player/enemy will add the entities to the screens in the map editor, for example the biter-spawner has the placable-player and placeable-enemy flags, if you go into the map editor and use 'f' to switch between player entities and enemy entities you will see that both have a creeper spawner if you were to place one of each in the map (along with a player) and then save/play it you would see the creepers attacking each other since they are on opposing forces. On the other hand if you were to add the "placeable-neutral" flag and (after restarting factorio if you left it running) place one next to the two previous spawners, the neutral creepers would neither attack the other creepers nor be attacked by them.
"placeable-off-grid"
placeable-off-grid refers to the fact that most entities are placed on an invisible 'grid' within the world, entities with the placeable-off-grid flag do not have to line up with this grid (like trees, players, creepers, and land-mines)
"pushable"
Pushable means that the entity can be 'pushed' by the car.
"player-creation"
This is not currently used, but adding this flag will make creepers destroy everything they encounter that is a "player-creation", depending on their priority (they would probably attack the turrets first and then other items) when instead of the freeplay using distraction=defines.distraction.byenemy it uses distraction=defines.distraction.byanything
"breaths-air"
This is used to specify that the entity breaths air, and so is affected by poison (currently Poison Capsules are the only source).
"not-repairable"
Used to specify that the entity can not be 'healed' by repair-packs (or construction robots with repair packs)
"building-direction-8-way"
Uses 45 degree angle increments when selecting direction (also, 8 point compass North-NorthEast-East-SouthEast-South-SouthWest-West-NorthWest). I think, correct this if know otherwise :) ~FreeER (talk)
"filter-directions"
Used to automatically detect the proper direction, if possible. Used by base with the pump, train stop, and train signal.
"fast-replaceable-no-rotate-only"
Used to prevent fast replacement of objects with the same name. Currently only used by base with the basic underground transport belts.
Example
flags = {"placeable-neutral", "player-creation"}