Based on Uefi/UefiGpt.h file, original notice:
EFI Guid Partition Table Format Definition.
This is the include file for any module of type base. Base modules only use types defined via this include file and can be ported easily to any environment. There are a set of base libraries in the Mde Package that can be used to implement base modules.
Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved. This program and the accompanying materials are licensed and made available under the terms and conditions of the BSD License which accompanies this distribution. The full text of the license may be found at http://opensource.org/licenses/bsd-license.php
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
EFI Partition Table Signature: "EFI PART".
The primary GUID Partition Table Header must be located in LBA 1 (i.e., the second logical block).