In case anybody else is wondering, here's the key for the letters on the map:
C = Communities
P = Parks
R = Reserves
S = Sanctuaries
D = Developments of Distinction
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International Dark Sky Communities
Communities are legally organized cities and towns that adopt quality outdoor lighting ordinances and undertake efforts to educate residents about the importance of dark skies.
International Dark Sky Parks
Parks are publicly- or privately-owned spaces protected for natural conservation that implement good outdoor lighting and provide dark sky programs for visitors.
International Dark Sky Reserves
Reserves consist of a dark “core” zone surrounded by a populated periphery where policy controls are enacted to protect the darkness of the core.
International Dark Sky Sanctuaries
Sanctuaries are the most remote (and often darkest) places in the world whose conservation state is most fragile.
Dark Sky Developments of Distinction
Developments of Distinction recognize subdivisions, master planned communities, and unincorporated neighborhoods and townships whose planning actively promotes a more natural night sky but does not qualify them for the International Dark Sky Community designation.
C = Communities
P = Parks
R = Reserves
S = Sanctuaries
D = Developments of Distinction
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International Dark Sky Communities Communities are legally organized cities and towns that adopt quality outdoor lighting ordinances and undertake efforts to educate residents about the importance of dark skies.
International Dark Sky Parks Parks are publicly- or privately-owned spaces protected for natural conservation that implement good outdoor lighting and provide dark sky programs for visitors.
International Dark Sky Reserves Reserves consist of a dark “core” zone surrounded by a populated periphery where policy controls are enacted to protect the darkness of the core.
International Dark Sky Sanctuaries Sanctuaries are the most remote (and often darkest) places in the world whose conservation state is most fragile.
Dark Sky Developments of Distinction Developments of Distinction recognize subdivisions, master planned communities, and unincorporated neighborhoods and townships whose planning actively promotes a more natural night sky but does not qualify them for the International Dark Sky Community designation.
Source: http://www.darksky.org/idsp/