Add extra headers
Usually you can do it with templates:
<property name="header_stuff">
....
</property>
But sometimes you want to add it not in just one page, so you usually go to www/site-master.adp, but that is not really good to maintain modularity, so instead, now you can define within your package a tcl callback like this:
ad_proc -public -callback subsite::get_extra_headers -impl my_implementation {} {
return the stuff that should go into the html headers
} {
set scripts "...."
set tags "...."
set text_to_return $scripts
append text_to_return $tags
return $text_to_return
}