-option "loglevel" l "set loglevel (0-6)" int typestr="level" default="4" no
+option "loglevel" l "set loglevel (0-6)" int typestr="level" default="4" optional
option "filter" f "Specify filter.
May be given multiple times to 'pipe' the stream
-f 'compress --inertia 5 --damp 2'
"
-string typestr="filter_spec" no multiple
+string typestr="filter_spec" optional multiple
option "list_filters" L "print list of available filters and exit" flag off