+\S2{pscp-usage-options-backend}\c{-sftp}, \c{-scp} force use of
+particular protocol
+
+As mentioned in \k{pscp-usage-basics}, there are two different file
+transfer protocols in use with SSH. Despite its name, PSCP (like many
+other ostensible \cw{scp} clients) can use either of these protocols.
+
+The older SCP protocol does not have a written specification and
+leaves a lot of detail to the server platform. Wildcards are expanded
+on the server. The simple design means that any wildcard specification
+supported by the server platform (such as brace expansion) can be
+used, but also leads to interoperability issues such as with filename
+quoting (for instance, where filenames contain spaces), and also the
+security issue described in \k{pscp-usage-basics}.
+
+The newer SFTP protocol, which is usually associated with SSH 2
+servers, is specified in a more platform independent way, and leaves
+issues such as wildcard syntax up to the client. (PuTTY's SFTP
+wildcard syntax is described in \k{psftp-wildcards}.) This makes it
+more consistent across platforms, more suitable for scripting and
+automation, and avoids security issues with wildcard matching.
+
+Normally PSCP will attempt to use the SFTP protocol, and only fall
+back to the SCP protocol if SFTP is not available on the server.
+
+The \c{-scp} option forces PSCP to use the SCP protocol or quit.
+
+The \c{-sftp} option forces PSCP to use the SFTP protocol or quit.
+When this option is specified, PSCP looks harder for an SFTP server,
+which may allow use of SFTP with SSH 1 depending on server setup.
+