10A. built-in library calls
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As you may have noticed from previous sections, the piece of code
automatically linked to the start of your code, called the "initialisation code",
always opens the three libraries intuition, dos, graphics and (and sometimes
mathieeesingbas), and because of this, the compiler has all the calls to those
four libraries (including exec) integrated in the compiler (there are a few hundred
of them). These are up to AmigaDos v3.1 (v40). To call Open() from the dos library,
simply say:

handle:=Open('myfile',OLDFILE)

or AddDisplayInfo() from the graphics library:

AddDisplayInfo(mydispinfo)

it's as simple as that.