I am trying to identify a coordinate system used to give positions to caves in France.
The Emergence du Ressel is at 555,19 - 251,48 (decimal coordinates 44.56194, 1.77167) and Source de Landenouse is at 562,54 - 243,17 (decimal coordinates 44.48763, 1.8657).
I am unable to identify the (xxx,yy - xxx,yy) coordinate system. How do I convert from that?