Linedef Type

LineDefs control the interaction between the player and the level geometry at playtime. The following abbreviations are used:

Code	Meaning
W	Walk. Activated when the player walks across the front side.
S	Switch, activated when used by player (space bar
G	Gun, activated when shot by player.
	One time, can only be activated once.
R	Repeat, can be activated repeatedly.
M	Monster only can use this.