Is There a Guide for Writing XMMS Plugins?

Anthanos asks: "I was recently asked to put together a Winamp and an XMMS plugin to do some pretty cool things. Having never done plugin development for either I went to their respective webpages and began looking for samples and/or SDKs to make use of. Winamp provided very well put together documentation and SDKs, but I can't find anything similar for XMMS. Has any such documentation or guide been put together? All I have found reference to so far are existing projects. I was hoping for the equivalent of 'Hello World!' for XMMS."