vinculum

A vinculum usually has little to do with division; it’s used in fractions and to group together numbers just as parentheses are.

You might expect 10 ÷ 5 is the same as 10/5 is the same as 10 over a 5 with a vinculum between them, but each has its own eccentricities.

But it gets really tricky when people assume that a slash replaces a vinculum.

Where plus or minus signs occur in the numerator or denominator, brackets or a vinculum is used.—Tr.

Again, Benedict XIV. in that Breve is speaking de duplici gradu consanguinitatis, not de secundo gradu, and states that a dispensation would be null, in the petition for which only one vinculum was expressed, whereas there existed two—duplex vinculum.