These parameters control modification of corners of an Element geometry.
Available four types: Chamfered, Rounded, Scalloped and Cutout corners.
Each corner can be modified individually, except when the geometry is not quadrilateral (f. e. triangles, pentagons, etc…). When the shape is not quadrilateral, you can use the value (and type) of the Top Left.
Corner Join – Set the join type for corner stroke: Smooth or Mitre (straight). Affects only Preview geometry.