Ligne

Ligne (l or triple prime (‘‘‘)) is a equal to  of an  or 2.11 s. Ligne is an old unit of length used exclusively in France, that's why it is also called Paris line. Line can be used as an alternative to millimeter to measure small things, such as insects. It can be used as subdivision of inches when measuring person's height, often designated using triple prime, for example 5'4"11‘‘‘.

Ligne in this sense is not to be confused with homonym line, which is of an inch.