How is data stored on disk? - EFI GUID

Question

I posted this question earlier on SuperUser but I feel it is more suited for programmers.

If I understand correctly, according to GPT, the first 16 bytes of LBA 2 is the

Answer 1

EFI_GUID datatype is declared as follows:

typedef struct {
  UINT32  Data1;
  UINT16  Data2;
  UINT16  Data3;
  UINT8   Data4[8];
} EFI_GUID;

Because original EFI architectures (IA64 LE and IA32e) were little-endian by default, so are the integers. I haven't really seen an UEFI implementation on big-endian machine, so I don't know if standard GUIDs will be stored otherwise.