Civil Service Fast Stream Applications

I would like to apply for the civil service fast stream scheme in Autumn when applications open again. I was wondering if it is possible to apply for more than one scheme at once, or if you can only apply for one at a time? Eg, the Diplomatic Services scheme, as well as the Social Research scheme, and maybe others. On their website it says you can only apply once per an application season but I don't know if this means once per a scheme or only one scheme. Thanks for any help!