Pjson uses these things (lines 64-123), and I'm not quite sure where to search for what they do or represent. Is there a name for it that I can google?
From the word "serialize" I thought it was some method of serialization, but according to this answer, it doesn't look at all like what it's trying to do.
//pjson.h
// This template utilizes the One Definition Rule to create global arrays in a header.
   template<typename unused=void>
   struct globals_struct
   {
      static const uint8 s_str_serialize_flags[256];
      static const double s_pow10_table[63];
      static const uint8 s_parse_flags[256];
   };
   typedef globals_struct<> globals;
   template<typename unused>
   const uint8 globals_struct<unused>::s_str_serialize_flags[256] =
   {
   //...
   };
   template<typename unused>
   const double globals_struct<unused>::s_pow10_table[63] =
   {
      // ...
   };
   // bit 0 (1) - set if: \0 cr lf " \
   // bit 1 (2) - set if: \0 cr lf
   // bit 2 (4) - set if: whitespace
   // bit 3 (8) - set if: 0-9
   // bit 4 (0x10) - set if: 0-9 e E .
   template<typename unused>
   const uint8 globals_struct<unused>::s_parse_flags[256] =
   {
     // ...
   };
 
    