grdcontour(1) on Linux
The text 62a97df1eb2e, as Debian 2.2 (Potato) shipped it.
contouring of 2-D gridded data sets
Flags it lists
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-A -
-B -
-C -
-D -
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-G -
-J -
-K -
-L -
-M -
-N -
-O -
-P -
-Q -
-R -
-S -
-T -
-U -
-V -
-W -
-X -
-Y -
-Z -
-bo -
-c