Excellent post tada, with one minor correction needed....instead of 9, it's actually 12, the main TSX and eleven more alternates. Here they are, with the Letter Symbol and then name....excluding the main TSX which goes by T.
1. U-NEO ATS
2. A-Alpha
3. O-Omega
4. P-Pure
5. X-Chi-X
6. H-CX2
7. D-CXD
8. L-LiquidNet
9. M-TriAct
10. I-Instinet
11. Y-Lynx