Linedef Attributes

The different settings control whether the linedef can be crossed and how/when it appears on the map. They also control the method of displaying textures.

Attribute	Description
Impassable	Neither players nor enemies can cross.
Block Enemies	Only Enemies cannot cross.
Two Sided	The linedef has 2 sides
Upper Unpegged	The texture is rendered top down instead of bottom up.
Lower Unpegged	The main and below textures are rendered bottom up instead of top down.
Secret	The linedef will not appear on the player’s map in red. This protects secret doors and other hidden features. It has nothing to do with the secret sectors.
Block Sound	Sound will be blocked by the second linedef of this type encountered. This can be used to facilitate ambush situations and the like.
Never On Map	The linedef never appears on the player’s map — even with the map power-up.
Always On Map	When the level is started, the linedef will be on the player’s map before the player has seen it.
Use Works Thru	BOOM only (see BOOM docs)
HEXEN ZDOOM only
Repeatable	Designates whether a linedef type (if any) is repeatable? In DOOM, only some types were repeatable, HEXEN let’s you decide.
Activated When	Activated as noted by Players, Monsters and Projectiles
Activated Monster+Play	Activated by both Monsters and Players
Blocks Everything	Blocks everything (including missiles)
Player Pass Thru	ZDOOM only (see ZDOOM docs)