Originally Posted by bulgie

The five 10 mm holes outboard of the 86 mm BCD holes are at 122 mm BCD. This means a 99 ring of that type can be used as a middle "triplizer" ring on a Stronglight 93 or other 122 BCD crank. I don't think they intended for it to be used that way, it's just a happy accident. I think they had the die for punching holes at 122 mm, so some clever industrial designer said "eh, why not just punch some holes there with this punch we have already, little lighter and looks nice..."

To use it as a triplizer, you need to counterbore the 122 mm holes, or else the chain will hang up on the protruding head of the chainring nuts. You also need to saw off the five little shelves on the backside of the spider arms on the 93 crank, similar to making it into a track or 1x crank. Here's a modest example:

Mark B in Seattle