It is an emblem of Lorraine in eastern France. It was originally held to represent Joan of Arc and later used in various patriotic contexts. It is a modified Latin cross where the upper bar represents the sign bearing the Latin inscription INRI.
A cross consisting of a vertical bar intersected by a shorter horizontal one above its midpoint, and again by another horizontal bar half the length of the first, intersecting the vertical bar midway between the larger horizontal bar and the top of the vertical bar: ⟨☨⟩.
cross of Lorraine on Wikipedia.Wikipedia 