ALPC.H

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

d:\th\minkernel\ntos\inc

and draws from it the following type definitions:

Line Number Type
99 struct _ALPC_COMPLETION_LIST_STATE
101 unnamed union u1 in _ALPC_COMPLETION_LIST_STATE
103 unnamed struct s1 in u1 in _ALPC_COMPLETION_LIST_STATE
125 struct _ALPC_COMPLETION_LIST_HEADER

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