MdeModulePkg[all]  0.98
 All Data Structures Files Functions Variables Typedefs Enumerations Enumerator Macros Pages
gEfiStandardErrorDeviceGuid

Guid specifiy the device is the StdErr device.
Include/Guid/StandardErrorDevice.h

GUID Information

GUID's Guid NameGUID's Guid
gEfiStandardErrorDeviceGuid{ 0xD3B36F2D, 0xD551, 0x11D4, { 0x9A, 0x46, 0x00, 0x90, 0x27, 0x3F, 0xC1, 0x4D }}

Refer to Header File

MdeModulePkg/Include/Guid/StandardErrorDevice.h