[OSM-talk] Rendering subareas?

[Alex S.]

I have a question about how subareas should be addressed so they are 
properly rendered.

For example, there is a park in my city that has several sport courts 
(pitches, for the britishly inclined) inside it as subareas.  This 
particular park has several tennis courts, baseball diamonds, soccer 
fields, a running track, etc.  However, these fields are sub-parts of 
the park as a greater whole.  This is common in the USA.

Is there a special way to mark these so that they are rendered properly? 
    (I believe it has been noted that using 'level=*' is frowned upon, 
as these features are not physically 'above' or 'below' each other.) 
Or, does there need to be a change in the rendering ruleset instead?

The park in question is located here:
http://www.openstreetmap.org/?lat=47.66932&lon=-122.34368&zoom=16&layers=B0F

I have already marked the location of the tennis courts, but it is 
obviously being overlaid by the park itself in both the osmarender and 
mapnik layers.