This macro is used to create blocks used when formatting numbers. The definition from rt_locale.h and sample code are shown in Example 2.20.
For all the macros, the first two arguments are a symbol prefix and a locale name. The resulting locale block is addressed by the expression &symprefix_start, and the index entry by the expression &symprefix_index.
Example 2.20. LC_NUMERIC_DEF
#define __LC_NUMERIC_DEF(sym,ln,dp,ts,gr) static const int sym##_index = ~3 & (3 + (sizeof(dp)+sizeof(ts)+sizeof(gr)+ 20) + (~3 & (3 + sizeof(ln)))); static const char sym##_lname[~3 & (3 + sizeof(ln))] = ln; static const int sym##_pname = ‑4‑(~3 & (3 + sizeof(ln))); static const int sym##_start = 12; static const int sym##_tsoff = (sizeof(dp)+12); static const int sym##_groff = (sizeof(dp)+sizeof(ts)+12); static const char sym##_dptxt[] = dp; static const char sym##_tstxt[] = ts; static const char sym##_grtxt[] = gr;