IAR library building

XAR Library builder: Combine a set of UBROF object files into a library file.
XLIB librarian: can do a number of things in addition to building libraries: modify the size and contents of existing libraries, list information about individual library modules, and more.
--> Both tools use the UBROF standard object format(Universal Binary Relocatable Object Format).

XLIB功能多於XAR, 若只是單純的把數個Object file(UBROF)作成一Library, XAR便已足夠了。