In addition to this documentation, there are a number of other resources available related to Escape development. Because it's API is based on Ascape, a lot of resources developed for Ascape are equally applicable to Ascape. The Ascape documentation is bundled with some distributions of the AMP tools, but if you are using the Eclipse AMP download, you can access it online or install it from the Ascape update site.
There is a complete Javadoc as well as an excellent manual and other web resources. See the Ascape Website for general information.