Slave Child and Parent are types of Classes, Child classes are derived from parent classes, its called inheritance, Im not too sure about slave classes, but apparently they are used in data bases, like Oracle. RFU is named for the wireless unit, its a Radio Frequency Unit. that file handled all the wireless functions. IMHO its just debug stuff left over like what one guy said up there... Yea that shows they have good naming habits that anyone can understand what each file or class and function does... But strangely C does not use classes, but Unions and Structs, classes are a C++ thing...
edit: the NULL.size is the size of the ping that gets returned when the RFU (see above) sends the data, so I assume the function is literally called RfuFunc in the class named RFU, so I assume that RFU function is the constructor... and Im not too sure but I think the RFU (Wireless adapter) brings in the info thats highlighted like RFU WAIT, RFU SEND, RFU BOOT, RFU ERROR and ect to set permisions, allowing the game to do certain functions already implemented on the wireless adaptor...
edit of an edit: None of try to disassemble that, trust me, its just a pain in the ass, you end up with whole bunch of assembly code, and you will get nowhere... You can only get a glimpse of how they handle the wireless on the GBA...
triple edit: The RFU WAIT and other functions are the ones that they were watching (its when you debug, you keep track of watch they are doing) and left over from the debug