Select Edge

Although the node is designed to select edges, it cannot always cope with this. There are 3 modes in the node.
By the number of vertexes, by the angle between the polygons, and by the mesh border..

Settings

Domain menu – Point, Edge, Face, Face corners
Menu
Geometry –tries to define faces into geometries depending on the threshold
Bezier – Trying to determine the sharp angles of the Bizier curve.
Mode Menu

• Face boundaries – along the border of the island
• Vertex Count – number of adjacent vertexes,
• Edge Angle – angle between the polygons

Invert – inverting the selection
Vertex less – Choosing where the number of vertexes is less than the value.
Threshold – For the edge angle mode, selects when the value is greater than the threshold

Sometimes domain change may not work from the node, so just call the domain change node additionally.

How to use

Note that the angle is determined only for a curve with the Bizier type.