The variable *unit-transform*
holds the list (1 0 0 1 0 0)
which is the unit transform I, such that X = XI, where X is a 3-vector. Graphics ports are initialized with the unit transform in their
graphics-state
. This means that port coordinate axes are initially the same as the window axes.
CAPI User Guide and Reference Manual (Unix version) - 3 Aug 2017