The pvmd and libpvm use the same message header,
shown in Figure 
.
Code
contains an integer tag (message type).
Libpvm uses
Encoding
to pass the encoding
style of the message, as it can pack in different
formats.
The pvmd always sets Encoding (and requires that it be set)
to 1 (foo),
Pvmds use
the
Wait Context
field
to pass the wait id's (if any, zero if none)
of the waitc
associated with the message.
Certain tasks (resource manager, tasker, hoster)
also use wait id's.
The
Checksum
field is reserved for future use.
Messages are sent in one or more fragments,
each with its own fragment header (described below).
The message header is at the beginning of the first fragment.
