Thats weird thing to do, considering the documentation says The default set of characters to encode are control chars, high-bit chars, and the <, &, >, and " characters..
Reading the source would also be better

  } else {
    # Encode control chars, high bit chars and '<', '&', '>', ''' and 
+'"'
    $$ref =~ s/([^\n\r\t !\#\$%\(-;=?-~])/$char2entity{$1} || num_enti
+ty($1)/ge;
    }
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