This keyword, like the globals, breed, <breed>-own, and turtles-own keywords, can only be used at the beginning of a program, before any function definitions. It defines the variables that all patches can use.
All patches will then have the given variables and be able to use them.
All patch variables can also be directly accessed by any turtle standing on the patch.
See also globals, turtles-own, breed, <breeds>-own.
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