research only could be wrong;plenty of others in the know who...

research only could be wrong;
plenty of others in the know who wont reply.
but a very worthwhile exercise to find out what exactly is going on....beyond my mental sometin

https://openmarkets.com.au/compare-platforms
this gives a good comparison, from my searching;

so charts that are free on the web, use asx tradematch
also other paying sites only use tradematch.

more expensive sites like commsec iress; use ASX Trade Match, ASX Centre Point Chi-X Mid Point

so it depends on the provider and its no good asking the ASX as they told me to ask the provider.
google this asx-information-vendors-guide

https://www.asx.com.au/services/trading-services/australian-cash-market-report.htm

all trades are processed through the one exchange ASX monopoly; - shows dark lite on off;
chi-x is complaining about asx monopoly. new blockchain asx exchange .
So how are developers planning on using the ASX’s distributed ledger technology (DLT) platform? To bring registry management in-house; to automate proxy voting, so AGM votes can be cast with the click of a button; for the real-time management of capital raisings; to facilitate superannuation switching by by-passing pooled unit structures; to mutualise KYC; to re-engineer procurement processes; and to digitise the home-buying experience, just to name a few.
https://www.computerworld.com/article/3459923/vmware-to-back-asx-blockchain-push-in-australia-and-nz.html

looks like average 80.9% of data on the asx is tradematch charts this week;
so that's just enough for me statistically,
dark lite 70% 30% ?? dont know
if it was only 70% then its not enough data statistically to make a well informed decision.

stocks may be 60% tradematch and 40 % the rest at times.. calculated on just on a couple stock comparisons.
the free charts dont show 40% of data at times

chi-x is day only and depth gets wiped