-the filename extension, so ``export_block foo.png``, ``export_block
-foo.eps``, and ``export_block foo.txt`` will save PNG, EPS, and
-TAB-delimited text files respectively.
+the filename extension, so ``export_block --output foo.png``,
+``export_block --output foo.eps``, and ``export_block --output
+foo.txt`` will save PNG, EPS, and TAB-delimited text files
+respectively.
+
+.. todo:: Currently no PNG or EPS output, use the GUI and the plot
+ panel's toolbar for non-text exports.