access function in strings.maps

["Dennis W. Butler" <dbutler@calpoly.edu>]

I've been exploring the string handling capabilities of Ada95 and have
stumbled across a Thing I can't figure out. In the strings.maps package
(LRM section A.4.2), there is a type definition that reads:

type Character_Mapping_Function is access function (From : in character)
return character;

I would have thought a Character_Mapping_Function would be more like:

function Character_Mapping_Function (The_Map: in Character_Mapping;
Domain_Character: in Character) return Character; -- range character

Although I read LRM section 3.10, I couldn't figure out the access
function type definition. Where can I get an explanation of what the
type definition does and how I can use it? I did note that the LRM says
that the Character_mapping_Function is used for transformational
mappings in the Translate subprograms...does this mean I'm not supposed
to worry about it?

Thanks,

Dennis Butler
Computer Science Department
Cal Poly, San Luis Obispo