France Caisse D'amortissement Sinking Fund Stamps

There seems to be some confusion about these, based on how you see them listed by dealers.

France maintained a sinking fund to reduce national debt a few times in its history. The period we care about as stamp collectors started in 1927 and lasted for five years. Scott lists these as semi-postals, and most were overprints on existing stamps. You'll run across C A overprints, and these, Caisse d'Amortissement:



This looks to be a vertical margin pair from the 1929 issue. Too bad about the crease, but still an attractive piece.

Some of these have a healthy CV, so I assume we have to watch out for forged overprints.

Please post up some more, or any additional background on the fund, the stamps, or how to evaluate the overprints.

I have a few but still need a couple more year sets.