Please help me refresh my memory:

Before MPE/XL (now MPE/iX) in BUILDs and FILEs we used to specify

        -- blocking factor (and we ran CSL programs to calculate the
        optimum blocking factor!)

        -- number of extents and initial extent allocation

        example: BUILD ABCD;REC=-80,16,F,ASCII;DISC=100000,32,8

At some point on XL, we learned that the file system ignored both of these
specifications and started omitting them. In fact MPE/iX allocates file
storage in 4k pages.

        example: BUILD ABCD;REC=-80,,F,ASCII;DISC=100000

        However, to allocate a file fully up front, the following would
        work:

        BUILD ABCD;REC=-80,,F,ASCII;DISC=100000,32,32

        except that the resulting number of extents would not necessarily
        correspond to 32,32

There was one issue with extents: if the file was destined for a Classic
machine, the number of extents had to be specified, had to be <=32 and the
resulting extent size had to be compatible with the maximum extent size of
a Classic machine (the value of which I have stored out of my head).

Am I correct that now MPE/iX does its own thing with blocking factors and
with extent allocation -- regardless of specifications (save the 32,32) and
that a blocking factor display in LISTF is only for compatibility reasons
and is not "real"?

Does either of these specifications matter if the file is destined for some
other hardware, e. g., IBM? And if either does matter will it still be
ignored?

Thanks,

====================
Leonard S. Berkowitz
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