The codimension-three conjecture states that any regular holonomic module extends uniquely beyond an analytic subset with codimension equal to or larger than three. We give a sketch of a proof of this conjecture.
"On the codimension-three conjecture." Proc. Japan Acad. Ser. A Math. Sci. 86 (9) 154 - 158, November 2010. https://doi.org/10.3792/pjaa.86.154