I'm working on a glossary operator for templates, so when I saw the incude line I had to investigate it. If you track that call, it'll go to link.tpl and that's where the answer is as well.
enable_glossary refers to the SDK tab (as you can see on sdk.ez.no) and enable_help refers to the Manual pages. Or was it the other way around? :) Both default to off in standard installs.
If these variables are set to true() they the link.tpl template will add some
<link rel="" href=""> tags to the header. The <link> tags are hints which the web browser can use, for instance Opera 7 uses this to create a top bar with Home, Index, Search, Glossary etc. Lynx will also use these tags and display them at the top.
For instance try Opera 7 or Lynx on ez.no. (You might have to enable it in Opera 7, View/Navigation Bar/Auto should do it)
If you enable glossary and help, the sdk and manual will be added.