The following quote is from page 4-27 of the MSCP Basic Disk Functions Manual
which is part of the UDA50 Programmers Doc Kit manuals:

As stated above, the host area of a disk is structured as a vector of logical
blocks.  From a performance viewpoint, however, it is more appropriate to view
the host area as a four dimensional hyper-cube, the four dimensions being
cylinder, group, track, and sector.

    ...

Referring to our hyper-cube analogy, the set of potentially accessible blocks
form a line parallel to the track axis.  This line moves parallel to the sector
axis, wrapping around when it reaches the edge of the hyper-cube.

Yea, though I walk through the valley of the shadow of APL, I shall fear no
evil, for I can string six primitive monadic and dyadic operators together.
		-- Steve Higgins

How many seconds are there in a year?  If I tell you there are 3.155 x 10^7,
you won't even try to remember it.  On the other hand, who could forget that,
to within half a percent, pi seconds is a nanocentury.
		-- Tom Duff, Bell Labs