The wire package provides for sending data along wires. The remote package sits on top of this package. All data sent with a given output routine must be read in the remote process with the complementary fetching routine. For example, if you send so a string with wire-output-string, the remote process must know to use wire-get-string. To avoid rigid data transfers and complicated code, the interface supports sending tagged data. With tagged data, the system sends a tag announcing the type of the next data, and the remote system takes care of fetching the appropriate type.
When using interfaces at the wire level instead of the RPC level, the remote process must read everything sent by these routines. If the remote process leaves any input on the wire, it will later mistake the data for an RPC request causing unknown lossage.