void calendar_offset_to_gregorian (int ofs, int *y, int *m, int *d, int *yd);
int calendar_offset_to_year (int ofs);
int calendar_offset_to_month (int ofs);
void calendar_offset_to_gregorian (int ofs, int *y, int *m, int *d, int *yd);
int calendar_offset_to_year (int ofs);
int calendar_offset_to_month (int ofs);