<para>The third parameter is optional. It is used to give each TWKB-geometry an unique ID</para>
<para>The fourth parameter is optional. If it is set to true, the size of the geometry is included</para>
<note>
- <para>TWKB is still a moving target. The format is described <ulink url="https://github.com/nicklasaven/TWKB">https://github.com/nicklasaven/TWKB</ulink> , and code for building a client can be found <ulink url="https://github.com/nicklasaven/twkb_web">https://github.com/nicklasaven/twkb_web"</ulink></para>
+ <para>TWKB is still a moving target. The format is described <ulink url="https://github.com/TWKB/Specification">https://github.com/TWKB/Specification</ulink> , and code for building a client can be found <ulink url="https://github.com/TWKB/twkb.js">https://github.com/TWKB/twkb.js</ulink></para>
</note>
<note>
<para>TWKB doesn't make any difference of Z and M. So PointM and PointZ will give the same twkb representation.</para>