These directories contain the source and libraries for the IRAF system, i.e.,
the system interface or "virtual operating system" (VOS) and the machine
independent i/o libraries comprising the program interface.  To rebuild the
VOS merely run "mkpkg" after bringing up the bootstrap utilities and libraries
in host$.  To relink the system executables after an important modification
to the VOS, type "mkpkg update".

    clio	command language i/o
    dbio	database i/o
    etc		miscellanous system modules
    fio		file i/o
    flib	contains nop.x, used to list modules for libmain.o
    fmtio	formatted i/o
    gio		graphics i/o
    imio	image i/o
    ki		kernel inteface (networking)
    memio	memory i/o
    mkpkg	descriptor file for the MKPKG utility
    mtio	magnetic tape i/o
    osb		bit and byte primitives
    spool	record of the last sysgen
    vops	vector operators

For example:

	mkpkg >& spool &		make or update the VOS libraries
	mkpkg update			update the system executables