Space is a delimiter between fields and is simply the space character. Type is a one byte token character that denotes the type of this packet. Finally, msg is the Tcl command to be evaluated. This callback reads the message, buffering partial reads if necessary. If the packet is an RDO, the command is evaluated.
Nothing is returned to the sender.
If the packet is an error code or a return value, the id field is used as an index into the activation record for the RPC, which is described below. It is stored in a table, using id as an index. To understand the function of the activation record, consider the following example. This loop exits immediately, since the activation record indicates the RPC is received. The surprising thing about the mechanism is that its expression in C is extremely elegant.