Wikimedia Bugzilla is closed!

Many external programs that would be handy from custom extensions have both a data set that drives them, and a bunch of 
attributes that modify how the data set is interpreted.

For example, Graphviz has a simple data format, but there are several layout engines available. You don't really want to 
pollute the data with such metadata. Another example is Ploticus, which has a simple data format, modified by a slew of 
command line switches.

I propose the following XML-compatible extension to extensions:

<ext key1=value1 key2=value2 ... > (extension data goes here) </ext>

The key/value pairs are packaged up in an associative array and passed as an optional second argument to the registered 
extension function.

For example:

<somethingThatDrawsImages style="float:right"> would allow graphics to be better integrated with pages
<graphviz layout=neato> would allow non-hierarchical layout