OMathFunction.BorderBox (Word)

Returns an OMathBorderBox object that represents a border drawn around an equation or part of an equation. The BorderBox object can also be used to draw horizontal, vertical, and diagonal strikethrough lines through the BorerBox arguments.

Dim omf As OMathFunction: Set omf =  
Dim ombBorderBox As OMathBorderBox
Set ombBorderBox = omf.BorderBox