GDSII Paths (lines with width) need to be mitered when they bend at certain angles so as to prevent the corner of the bend from protruding excessively. Each software tool has its own approach to mitering since the formula for mitering is not part of the GDSII specification.
For paths that do not bend sharply the corner extension can be calculated by extending the edges of the path until they meet as shown below:
As the angle of the bend (measured from the interior) becomes less than 90 degrees, the simple miter approach is less useful as the protrusion becomes excessive as shown below:
The GDSRIP program uses a different rule when mitering paths with bends (measured from the inside) of 60 degrees or less as shown below:
