func_ladder
func_ladder is a brush entity available in all 
GoldSrc games.
…
A ladder. Players will be able to freely move along this brush, as if it was a ladder. The most common way to build a ladder is to first construct it out of brushes (or an masked-textured brush) and then place the func_ladder over it. Only the brush construction will be visible in the game.
Key Values
Targetname:
- Name
(targetname)<targetname> - The targetname that other entities refer to this entity by.
