straightedge

n.

画直线用尺；直尺；

Straightedge
Straightedge
Straight edge
Adjustable angle and miter finder
Chalk line device
Tomahawk (geometric shape)
Philo Line
Napoleon's Problem
“How Edge Are You?” Constructing Authentic Identities and Subcultural Boundaries in a Straightedge Internet Forum
Rave and Straightedge, the Virtual and the Real: Exploring Online and Offline Experiences in Canadian Youth Subcultures.
The Straightedge Youth Sub-Culture: Observations on the Complexity of Sub-Cultural Identity
Compass and Straightedge in the Poincaré Disk
Compass and Straightedge in the Poincar′ eD isk