There's nothing to read, it's just my own personal mapping style! I make use of osmuk cadastral parcels to trace landuse according to property boundaries. Basically anything that's part of a private residence inc. garden and driveway goes inside residential landuse and everything else doesn't (multi-property garages, pavements, shared parking areas). Any argument will be over whether mapping to that level is a good use of time, but certainly there's nothing wrong with adding more detail in the way I have done. The primary-tertiary example was here for Bristol only where my goal is to split up the multipolygon only, not to create extremely detailed landuse as I have done elsewhere.