[ink] orientation of 'width' measurement is undefined

Reference:
http://www.w3.org/TR/2006/WD-InkML-20061023/#width

The direction of a trace through a sample point is undefined.  You only have
a discrete sequence of Cartesian samples.

Better to describe traces with 'width' data as the envelope of a sequence
of circular dots of diameter given by the 'width' data.  The trace generated
by a circular brush of varying diameter.

Al