Gecado with a G, sorry about that! I think the name is pronounced She-card-oh.
Here in NSW, Australia a new permit for each purchase, two guns = two permits etc, $30 each permit.
Power is not mentioned with air guns.
Strangely I can get a permit called a 'Class A or B' to buy an air rifle, then go and buy a rimfire or shotgun with that permit which includes a 17HMR or .22WRM. With a permit for a rimfire or shotty, go and buy an air rifle with the permit. I have to tick one of those boxes on the form or they might send it back.
cheers
Ken