--a|at-least. Zero implies default behavior.
--d|delimiter
--equiv-header
--e|equiv
--equiv-start
Derived: --f|fields
--H|header
--i|ignore-case
Input files
Derived. True if no fields specified or '--f|fields 0'
--line-buffered
--m|max. Zero implies default behavior.
--number-header
--z|number
--r|repeated. Shorthand for '--atleast 2'
Container for command line options.