Linedef types, also commonly called specials, are actions done by linedefs (such as walls) when you press them as switches, walk over them, shoot them and so on. Switches and walk-over teleporters are examples of such specials.
Eternity supports both the classic Doom map format and the UDMF format. Depending on which editing format you choose, linedef types come in two categories: classic and parameterized. Classic ones merely have an action and a tag (so it does the specified action on all sectors with the same tag). Parameterized ones, however, have an action, up to 5 parameters (arguments) and an activation type (such as choosing between pressing or crossing it), being based on Hexen's more powerful model (whose versatile editing format was quickly adopted by earliest ZDoom versions, as a precursor to UDMF). Under the classic Doom format you can't natively place parameterized specials; you need the help of ExtraData for that. But under UDMF, you can only use the parameterized ones, easily, directly in the map editor.
If you map under UDMF, you only need to look up the parameterized specials. Otherwise, also look at the classic specials. Keep in mind that most of the classic ones are inherited from vanilla Doom and Boom, so a lot of the information on them should be familiar.
- Back to Editing reference
- 1 Overview
- 2 List of specials
A classic special only has an action number and a tag. Everything about the action is defined in that number: activation type (switch/cross/shoot), whether it requires a tag or will affect the sector behind it (doors vs switches) and whether it can be used by monsters. The tag is the number assigned to the targeted sectors. This is the same as in vanilla Doom.
Classic specials also include the Boom generalized specials, which allow greater customization in what they do, very close to the capability of the parameterized specials. As usual, all these "parameters" are encoded in the action number, typically a larger number, counting thousands (as opposed to non-generalized ones which are a few hundred at most).
A parameterized special has an action number, up to five parameters and user-settable mode of activation. Under the classic format, it can only be used along with ExtraData; under UMDF it's native. It should be familiar to you if you've been editing Hexen and ZDoom maps before.
Statically activated specials
Among both classic and parameterized there are a few specials which are activated at level startup instead of during the game when some event occurs (such as crossing). Examples are the Boom floor transfer special (which creates effects such as deep water) or the MBF sky transfer.