Stone, unknown technology [ST99] - jcgomezz/Building_taxonomy GitHub Wiki

It is clear that the structural material is stone, but the type of stone masonry is unknown. The build-up of the wall may be hidden, as in the case of a plastered wall, or information about it is unavailable.

This is a stone masonry building, but there is a mix of technologies - street facade was built in dressed stone masonry and the other exterior wall is built using random rubble stone masonry (Halifax, Canada, S. Brzev)