Mapnik zoom levels and detail

Zoom level that data first appears at (compiled by observation - feel free to add/amend)
Zoom level	Data first included at this zoom	Notes
5	railways, motorways, trunk, primary and secondary roads	-
6	-	-
7	tertiary roads	please add tertiary roads into the rendering stack somewhere below secondary and above everything else.
8	-	-
9	unclassified roads, rivers, ferries, green spaces (parks, woods), heaths	-
10	landuse (eg residential), more place names	-
11	lakes, reservoirs, motorway symbols	-
12	-	-
13	unclassified (as casement roads), primary and secondary roads named, footways/cycleways (grey)	-
14	footways, cycleways, unsurfaced roads	-
15	names for unclassified roads, feature names	-
16	pubs, parking	-
17	embassy	can this go to 16?
18	-	-

Mapnik - detail not rendered

lots of stuff in this trac query
parking areas are crappy
castle symbol doesn't exist
recycle symbol too
lots of green areas are rendered grey
- leisure=common
- leisure=garden
- leisure=golf_course
- leisure=pitch
- landuse=allotments
- landuse=cemetery (the crosses don't work properly, maybe plain grey/green aren't the best colour?)
- landuse=forest (darker green?)
- landuse=recreation_ground
- landuse=village_green
- natural=wood
none of the landuse areas are rendered differently, it might be useful to show retail / residential / commercial / industrial areas
streetmap.co.uk Reigate max zoom packs a lot in - what can we learn from them?
colour blindness - are walk/cycle/bridleways crappy for colour blind people?
streams currently appear as wide as rivers, making Hertfordshire look waterlogged.
railway=subway currently renders as a nondescript grey line.
water bodies in hyde park and regents park dont show up at high zoom
service roads could be better, they look kind of jarring IMHO
runways and taxiways should look nicer
white outline of areas, e.g. this water body: http://www.openstreetmap.org/index.html?lat=51.233623021933354&lon=-0.2118559592274252&zoom=16
waterway=riverbank produces two lines for the riverbank rather than a solid fill for the river

Footpaths: They show up as grey lines on higher zoom levels, when they shouldn't appear at all #293
Residential should be rendered like unclassified is (i.e. a thin line), until you zoom in, then both the same as a double line. Residential may be slightly different colour, possibly fill with light grey instead of white. #296
County Borders need to appear different to unclassified roads. Dashed lines would be more appropriate. #298
The railway=subway tag is not rendered as a railway. Instead it is just an ordinary white line. #353
railway="tram" is currently rendered as railway="rail". As a tram is most of time in the streets of a city, it could be rendered differently (perhaps a thin black line ?) #321
Names for leisure: sports_centre render under polygon #343
On further zoom levels (<17) in addition to the blue lines, cyclepaths also have a gray surrounding road which is unnecessary and makes them again seem more important than normal roads. #354
Could the coastline be rendered the same colour as rivers? At some zoom levels of 12 and lower is shown as a thin grey line: and then at higher zoom levels 13 & 14 as a white line, and at highest zoom levels as a white fill with grey outline #322
I believe there should be a distinction in the rendering of highway=unclassified vs highway=unsurfaced at higher zooms. See #380