finally multiplying the unit normals by an offset.
    The algorithm is implemented as the 
    <code>grid.offsetXspline</code> function in the
    'vwline' package for R.
  </p>
    <h2>
      <a name="Requirements">7. Technical requirements</a>
    </h2>
    <p>
    The examples and discussion in this document relate to 
    <a href="https://github.com/pmur002/vwline/releases/tag/v0.1-1">'vwline' 
    version 0.1-1</a>.
  </p>
    <p>
    This document was generated within a Docker container
    (see <a h