I have just run into the same issue here: https://bugs.python.org/issue38950

- I prefer Terry J. Reedy's "keyword arguments" as it is clear and consistent with "positional arguments".
- But Steven Bethard 's "flag arguments" looks fine since it is well known to shell users.
- Martin Panter's "options" looks okay since it is the standard name in GNU Coreutils (https://www.gnu.org/software/coreutils/manual/coreutils.html#Common-options). However I don't like it very much as it is still ambiguous: "options", like "optional arguments", still suggests something that is non required. And "options" is less consistent with "positional arguments" (nobody seems to have suggested "option arguments").
- Oliver Smith's "switches" does not look okay because it is not general enough since it is commonly restricted to Boolean arguments.

Anyway, the first 3 solutions are better than the current "optional arguments". What is blocking the approval of Martin Panter's PR?