applicability of ALPC_ATTRFLG_* flags

[440bx]

ntlpcapi.h defines 3 ALPC_ATTRFLG_* flags.

I am guessing those flags are the possible values of the AttributeFlags parameter of AlpcInitializeMessageAttribute but, that's just a guess. My question is: is that guess correct or are those flags applicable to something else ?

Related to the above question: do those flags also apply to the Flags parameter of AlpcGetHeaderSize or that parameter use a different set of flags ? if it uses a different set of flags, what are those flags ?

Thank you.