Thanks Rick, Wouter & all others who have either shed some light or posed new questions on the subject.
Wouter, you answered my original question with this :

"There is only one aspect that determine wether a headsail is a spinnaker or a hooter and that is the midgirth
measurement.

When this is less than 75 % of the foot => hooter
When this is more than 75 % of the foot => asym spi or gennaker."

Now, I`m not an F16 sailor so I`m not too concerned over the issues which have arisen between Rick & Wouter
regarding this issue, and I had no intention of things getting this far out of hand !

Rick, as Wouter says, you can have as flat cut as you like, you can roller-furl the thing, even stuff it in your
underpants if you like, whatever works for you. Just comply to the 75% rule and all will be forgiven.
Surely you can develop the hooter to conform to this rule without hurting it`s performance too much ?
It can then be called an assymetric spinnaker and you can go racing.

Cheers
Steve