is not clear; according to Kern,

Toevoegselen

s. v. = vīthi + antarikā, i.e. space in between two streets or midstreet MN.i.448; AN.i.124. Neumann (Mittl. Slg. ii.182) translates “Rinnstein” (i.e. gutter). Under antarikā we have given the translation “interval of lightning, thus taking it as vijju + antarikā. Quoted DN-a.i.34.

a very bold assumption: vīthy contracted to vijj˚!