base numbers for custom Toolbox gadget (RiscOS Cloverleaf project)

Hello,

I would to program several custom Toolbox Gadgets.
Where I can see the unclaimed MyCustomGadget_Base and MyCustomGadget_SWIBase values?
In other words which values I can use to avoid clash with existing gadgets?
I reading “Writing Toolbox Gadgets” application note 281 from Acorn but there is in nothing about unused numbers.

You need to request allocations via the allocation system. You will then be given the values to use.