yl_speak_up/fs

In general, files in here ought to provide exactly tow functions:

    yl_speak_up.input_fs_<FILE_NAME> = function(player, formname, fields)
        -- react to whatever input the player supplied;
        -- usually show another formspec
        return
    end

and:

    yl_speak_up.get_fs_<FILE_NAME> = function(player, param)
        -- return a formspec string
        return formspec_string
    end

The actual displaying of the formspecs and calling of these functions happens in show_fs.lua.

There may be no function for handling input if the formspec only displays something and only offers a back button or buttons to other formspecs.

Additional (local) helper functions may be included if they are only used by those two functions above and not used elsewhere in the mod. That is not a technical requirement but mostly for keeping things clean. These functions are usually not declared as local and may be overridden from outside if needed.

An exception to the above rule are the functions

    yl_speak_up.show_precondition
    yl_speak_up.show_action
    yl_speak_up.show_effect

because in those cases it was better for readability and context to have them in their respective fs/fs_edit_<precondition|action|effect>.lua files.