Define new varibale type in pgmspace for PROGMEM : structure in FLASH

Using Arduino Programming Questions
5

MHDfo:
In the PROGMEM documentation we can read :
PROGMEM keyword is a variable modifier, it should be used only with the datatypes defined in pgmspace.h.

Well that is strange advice. You can store anything in program memory:

#include <avr/pgmspace.h>

struct something_t
{
  int a;
  int b;
  long c;
};

const something_t PROGMEM something_in_flash = { 1,2,3 } ;