MaxScaleDenominator - plepe/mapnik GitHub Wiki
Activates the rule, if [ScaleAndPpi scale] < MaxScaleDenominator + 1e-6
Example:
<Style name="text">
<Rule>
<Filter>[place] = 'city'</Filter>
<MaxScaleDenominator>10000000</MaxScaleDenominator>
<MinScaleDenominator>2000000</MinScaleDenominator>
<TextSymbolizer name="name" face_name="DejaVu Sans Book" size="10" fill="#000" dy="0" halo_radius="1" wrap_width="0"/>
</Rule>
</Style>