Understanding v4l2-ctl flags

Hi,

I have a Logitech webcam under PWC.
I've managed to use v4l2-ctl to change come controls, but some of them seem to be unsupported.

v4l2-ctl reports the following flags

inactive
update
slider
write-only
** no flags at all **

e.g.

restore_factory_settings (button) : flags=update, write-only

What is the meaning of them?
I can guess that inactive means unsupported, but do I care about the others?

See the documentation for control flags:

http://hverkuil.home.xs4all.nl/spec/media.html#control-flags

'inactive' doesn't mean unsupported, it just means that setting the control probably will have no effect at the moment. E.g. setting the gain when autogain is selected doesn't do anything. Only when the autogain is turned off can you set the gain control.

Regards,

Hans