Shuffle Hopf algebra conjecture for multiple zeta values in positive characteristic

Let the MZV's in positive characteristic be the multiple zeta values over the coefficient field used in the source, viewed as a set carrying the relevant shuffle product. Shuffle Hopf algebra conjecture. The set of MZV's in positive characteristic can be equipped with a shuffle Hopf algebra structure. Such a structure would provide the algebraic framework for the shuffle product of positive-characteristic multiple zeta values; the source presents it as conjectural and does not state that it has been resolved.