Italian to English Tech/Engineering Construction / Civil Engineering Muratura

Mattoni interi means something like full bricks but what about the i e i ¾ ? The full sentence is a description of a skill in the building trade. Here is the full sentence:


Riconosce (descrive) e prende (calcola) * i e i ¾
mattoni interi*.

Elsewhere someone is decribed as chosing bricks "senza distinguere gli interi dai ¾"

I am stumped by this ¾.

Suggestions much appreciated.

Yorick Jenkins