<div dir="ltr"><div>There's a graphical interface for this in Richard Kinch's Metafog:</div><div><br></div><div><a href="https://www.tug.org/TUGboat/tb16-3/tb48kinc.pdf">https://www.tug.org/TUGboat/tb16-3/tb48kinc.pdf</a></div><div><br></div><div>When I contacted him about a license he confirmed that there are some research paper(s) waiting to be written.</div><div><br></div><div>William</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Feb 9, 2018 at 7:58 AM, Hans Hagen <span dir="ltr"><<a href="mailto:pragma@wxs.nl" target="_blank">pragma@wxs.nl</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span>On 2/9/2018 1:11 PM, Karel wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;padding-left:1ex;border-left-color:rgb(204,204,204);border-left-width:1px;border-left-style:solid">
Nice, Luigi,<br>
but the envelope seems to be quite new and not yet documented in mp manual?<br>
</blockquote></span>
it's more "old and still experimental" awaiting to be tested before being declared a documented feature<div class="HOEnZb"><div class="h5"><br>
<br>
Hans<br>
<br>
<br>
------------------------------<wbr>------------------------------<wbr>-----<br>
                                          Hans Hagen | PRAGMA ADE<br>
              <a href="https://maps.google.com/?q=Ridderstraat+27+%7C+8061+GH+Hasselt+%7C+The+Netherl&entry=gmail&source=g">Ridderstraat 27 | 8061 GH Hasselt | The Netherl</a>ands<br>
       tel: 038 477 53 69 | <a href="http://www.pragma-ade.nl" target="_blank" rel="noreferrer">www.pragma-ade.nl</a> | <a href="http://www.pragma-pod.nl" target="_blank" rel="noreferrer">www.pragma-pod.nl</a><br>
------------------------------<wbr>------------------------------<wbr>-----<br>
--<br>
<a href="http://tug.org/metapost/" target="_blank" rel="noreferrer">http://tug.org/metapost/</a><br>
</div></div></blockquote></div><br></div>