  The Minkowski question mark function, maping the unit interval to itself, is
a continuous, strictly increasing, one-to-one and onto function that has
derivative zero almost everywhere. Key to these facts are the basic properties
of continued fractions. Thus the question mark function is a naturally
occurring number theoretic singular function. This paper generalizes the
question mark function to the 216 triangle partition (TRIP) maps. These are
multidimensional continued fractions which generate a family of almost all
known multidimensional continued fractions. We show for each TRIP map that
there is a natural candidate for its analog of the Minkowski question mark
function. We then show that the analog is singular for 96 of the TRIP maps and
show that 60 more are singular under an assumption of ergodicity.
