GD: Meta Fox

[spadgy]

Anybody know how this works? If so I've got a few questions:

1) Obviously the 'P' is power-up, and the 'B' a bomb, but what is 'S'? And how do you use 'S'? It limits you to five.

2) What does the 'A' pick up do?

[spoot]

S - is used to "purchase" the higher end ships after you pass a level.
A - is autofire if I remember correctly