<para>If <userinput>read-at-once</userinput> >= 1, batch mode is enabled with that many sectors being read at a time.
A value of zero disables batch mode and switches to single read mode. Not all devices support batch mode; in that case
gpsbabel automatically switches to single read mode.</para>

<para>Under normal circumstances, the larger this number the faster the transfer.
Reducing <userinput>read-at-once</userinput> or even switching to single sector mode might help when you get
transmission errors/aborts.</para>
