Actually I think that any old green ink would have worked equally well. The point was to absorb the red laser that might have been scattered through the polycarbonate by the interaction of the laser reading the pits, and thus re-picked up by the laser, causing jitter.

Thankfully the engineers made a better product so we don't have to deal with that sort of BS anymore.

I used to use that old green pen on Cds to tame the nasty highs. Nowadays, the remastered Cds, SACD, etc. make listening enjoyable again. Remember, Tubes Rule, do NOT be a Solid State fool!