Ligatures does make sense, then, in that usage, but hadn't heard it before.

Also back in the student days in Arkansas, I saw numerous examples of stones home-made by people who were impoverished and sometimes semi-literate. These included at least one slab of cement with the inscription, including "bornd" on the given date, printed in with a finger, and at least one other cement slab with the information spelled out in imbedded glass marbles.