GUID Master Boot records are standard - as in Master Boot Record, but the partition table entry is rather different.  The partition type, as described in byte 4 is set to 0xEE and the partition start, bytes 8-11 are normally set at 1.  Sector 1 then has the complete partition information.

Sector 0

000000   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

000010   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

000020   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

000030   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

000040   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

000050   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

000060   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

000070   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

000080   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

000090   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

0000A0   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

0000B0   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

0000C0   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

0000D0   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

0000E0   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

0000F0   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

000100   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

000110   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

000120   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

000130   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

000140   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

000150   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

000160   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

000170   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

000180   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

000190   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

0001A0   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

0001B0   00 00 00 00 00 00 00 00 - 8C CC 51 6B 00 00 00 FE            ��Qk   �

0001C0   FF FF EE FE FF FF 01 00 - 00 00 6F 59 1C 1D 00 00    ������
   oY 

0001D0   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

0001E0   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

0001F0   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 55 AA                  U�

Sector 1

000000   45 46 49 20 50 41 52 54 - 00 00 01 00 5C 00 00 00    EFI PART 
\  

000010   E6 CB B4 84 00 00 00 00 - 01 00 00 00 00 00 00 00    �˴�   
      

000020   6F 59 1C 1D 00 00 00 00 - 22 00 00 00 00 00 00 00    oY    "      

000030   4E 59 1C 1D 00 00 00 00 - 4E F1 2A 90 7A 65 97 49    NY    N�*�ze—I

000040   86 05 CF CA DB 95 81 85 - 02 00 00 00 00 00 00 00    ���ە��      

000050   80 00 00 00 80 00 00 00 - B5 D7 E6 8B 00 00 00 00    �   �   ���   

000060   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00 

The rest of the sector is all zeros                 

               

0001E0   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

0001F0   00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00                   

EFI stands for Extensible Firmware Interface.  EFI is designed to improve upon the existing Partition table design, which in particular has a 32 bit limit on sector numbers. 32 bit addressing will allow for 2TB of disk. Although this is not a problem at the monet, 1TB disks are becoming common, and 2TB can not be far behind. The address fields are nw 64bit rather than32 bit.  This will give a few years grace in capacity