WHEA_X.H

The public symbol file NTKRPAMP.PDB for the original release of Windows 10 tells that the kernel is built with the WHEA_X.H header at

d:\th\minkernel\ntos\inc

and draws from it the following type definitions:

Line Number	Type	NTDDK.H	NTOSP.H
43	enum _WHEA_ERROR_TYPE	16111	51028
53	union _WHEA_ERROR_PACKET_FLAGS	16121	51038
66	enum _WHEA_ERROR_PACKET_DATA_FORMAT	16134	51051
123	struct _WHEA_ERROR_PACKET_V2	16191	51108

The header WHEA_X.H is not known in any Device Driver Kit (DDK) or Windows Driver Kit (WDK).