VTX will automatically do the following:
- extend edges towards their intersection (V and T)
- intersect / weld two crossing edges (X)
V2X places a new vertex at the (projected) intersection of two selected edges. Without modifying the existing geometry
XALL intersects / welds all selected edges. This is like the X mode of the VTX operating on many selected edges.
E2F extends one side of a selected edge towards a selected face.
BIX makes the bisector of two selected edges. The edges may share a vertex, but don't have to. Edges must be coplanar for the bisector to make sense. Notice: For both scenarios this function will make guide geometry which is not attached to the original geometry.
CCEN reconstructs a circle, the minimal requirement is that you can select 3 vertices of a degenerate circle. Useful for when you've deleted part of the circle geometry and want to find the centroid to place the 3d cursor, or if you want to make a circle with a different vertex count or radius.