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*