An excellent informative post, Hog!
Just to verify what you said, my final conclusion was that any shares can be lent for shorting if you have them showing up in your online accounts, because shares held in online accounts are held in street form. The only sure way, as Hog said, that your shares CAN,T be borrowed for shorting is if you take receipt of the actual share certificate. Nobody is gonna do that and I am certainly not going to.
I personally went through TD,s and RBC,s investing agreements, I am no lawyer, but I could see these agreements are worded in a way that allows them to lend out your shares for shorting purposes. And as Hog said, the different brokers pretty well agreed with this when they were pressured.
Anyhow, the recorded short position on us is very little, and I don,t think we will have to worry about that aspect much longer.