=item C<AUG_TYPE_CHECK> = 4
-Typecheck lenses (can be expensive).
+Typecheck lenses.
+
+This option is only useful when debugging Augeas lenses. Use
+of this option may require additional memory for the libguestfs
+appliance. You may need to set the C<LIBGUESTFS_MEMSIZE>
+environment variable or call C<guestfs_set_memsize>.
=item C<AUG_NO_STDINC> = 8
to securely wipe the device). It should be sufficient to remove
any partition tables, filesystem superblocks and so on.
+If blocks are already zero, then this command avoids writing
+zeroes. This prevents the underlying device from becoming non-sparse
+or growing unnecessarily.
+
See also: C<guestfs_zero_device>, C<guestfs_scrub_device>,
C<guestfs_is_zero_device>");
"\
This command writes zeroes over the entire C<device>. Compare
with C<guestfs_zero> which just zeroes the first few blocks of
-a device.");
+a device.
+
+If blocks are already zero, then this command avoids writing
+zeroes. This prevents the underlying device from becoming non-sparse
+or growing unnecessarily.");
("txz_in", (RErr, [FileIn "tarball"; Pathname "directory"], []), 229, [Optional "xz"],
[InitScratchFS, Always, TestOutput (