+# Options:
+# -v Increase verbosity. Default is 1.
+# -q Set verbosity ot 0.
+# -D Increase amount of debugging dump.
+#
+# -n "No action": stop after writing Cargo.toml.nailing~
+# everywhere, and do not run any build command.
+#
+# -T<arch> --target=<arch>
+# Specify target architecture. If <arch> starts with a
+# capital ascii letter, is an alias for some other arch
+# looked up in Cargo.nail and then in the builtin list:
+# RPI arm-unknown-linux-gnueabihf
+# Translates to a --target= option to the ultimate command,
+# unless that is a cargo subcommand which would reject it.
+#
+# -u | --cargo-lock-update
+# -U | --no-cargo-lock-update
+# Arranges to do a dance to allow Cargo.lock (or
+# alternative) to be updated in the source directory.
+#
+# The Cargo.lock and Cargo.toml are copied to the build
+# directory along with a skeleton just big enough to fool
+# cargo. After cargo has run, the resulting Cargo.lock is
+# copied back to the source tree.
+#
+# Makes no sense with in-tree builds.
+#
+# Default is no update unless the ultimate command is a
+# cargo subcommand which we know needs it.
+#
+# -m | --cargo-manifest-args
+# -M | --no-cargo-manifest-args
+# Controls whether we add cargo command line options
+# relating to finding Cargo.toml, to the command to
+# run.
+#
+# Default is true if we are doing an out-of- tree build,
+# unless we are updating the Cargo.lock (in which case the
+# only relevant files are to be found in the build directory).
+#
+# The arguments are
+# --manifest-path=<path/to/Cargo.toml>
+# --locked
+# --target-dir=target
+#
+# -T | --no-cargo-target-arg
+# -t | --cargo-target-arg
+# Suppress --target (or un-suppress it). Only useful with -m.
+# Done automatically when nailing-cargo sees that the cargo
+# subcommand is one which needs it, eg `fetch'.
+#
+# --online | -o
+# --offline | -O
+# Whether to allow cargo to make network access.
+# (nailing-cargo always passes --offline to cargo, unless
+# --online is in force). The default is offline,
+# unless the cargo subcommand is one which implies
+# online (currently, `fetch').