If a file-scope object or a function does not need to be visible outside of the file, it should be hidden by being declared as static. This creates more modular code and limits pollution of the global name space.
Section 6.2.2 of the C standard Standard [ISO/IEC 9899:2011] states:
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ISO/IEC 9899:2011 Section 6.2.2, "Linkages of identifiers"
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