He have a unique 10-strings tuning he developed a long time ago (I think in the 90´s):
it’s standard bass in inverted fifths and melody in fourths but uncrossed (so thicker strings are on the edges) but that’s not all ; bass is a standart low C-G-D-A-high E but melody is half-step below Matched-Reciprocal tuning, so the highest note is a B at fret 0, then F#-C#-G#-D#.
As highest notes are in the center of both part, the High B melody string act also as the 6th virtual bass string!

Bass
C
G up a 5th
D up a 5th
A up a 5th (unison with 4th string)
E up a 5th

Melody
B (up a 5th from Bass)
F# down a 4th
C# down a 4th
G# down a 4th
D# down a 4th

It’s like the Dual Bass Reciprocal but the join is from highest strings instead of bass registry.
Should we call it the Dual Melodies Reciprocal? The Thierry Carpentier tuning or simply the TC tuning?!