5.7 Request intro
By convention, requests which begin with a capital letter do not elicit
a response from the server, while all others do -- save one. The
exception is `gzip-file-contents'. Unrecognized requests will
always elicit a response from the server, even if that request begins
with a capital letter.
The term command means a request which expects a response (except
valid-requests). The general model is that the client transmits
a great number of requests, but nothing happens until the very end when
the client transmits a command. Although the intention is that
transmitting several commands in one connection should be legal,
existing servers probably have some bugs with some combinations of more
than one command, and so clients may find it necessary to make several
connections in some cases. This should be thought of as a workaround
rather than a desired attribute of the protocol.