3.2.4 Higher-Layer Triggered Events
When a request is received from a higher layer, the client MUST create a named pipe connection to the server as specified in section 2.1. If it is unable to do so, the higher-layer request MUST be failed. That is, in case of a failure to connect, the higher level MUST retry the connection.
A header MUST be pre-pended with fields set as specified in section 2.2.2.
For messages that are specified as requiring a nonzero checksum, the _ulChecksum value MUST be calculated as follows:
The contents of the message after the _ulReserved2 field in the message header MUST be interpreted as a sequence of 32-bit integers. The client MUST calculate the sum of the numeric values given by these integers.
Calculate the bitwise XOR of this value with 0x59533959.
Subtract the value given by _msg from the value that results from the bitwise XOR.