Not only is internalization used in Canada it is a priority:
"
Orders traded anonymously are marked with the placeholder identifier “01”. While regulators such as Market Regulation Services Inc. and
the TSX manage the identities and owners of the anonymous trades, the market
itself never knows the actual identity of the brokers using the identifier
“01”. This has interesting repercussions for information trading; while many
models of trader activity account for a trader’s unwillingness to divulge information,
the anonymous trading system easily allows traders to alternately
trade publicly or anonymously.
Another aspect of the TSX that is unique is its internalization mechanism for
matching orders. In general, the mechanism for matching orders follows the
procedure that was described earlier. However, if there are multiple orders at
the same price, then priority is given, not by the time an order was entered,
but whether the orders’ broker numbers are the same. Orders with matching
broker numbers are executed first, and only then is time priority used. If a
broker uses the placeholder identifier “01”, then the internalization mechanism
is never used.
(from the Universiy of Waterloo)
JYD