adx reg halt, page-4

MCV1, here's a link and the section which about Regulatory Halts contains other links. Hopefully that will help.

https://www.asxonline.com/intradoc-cgi/groups/trading_and_market_information/documents/communications/asx_031976.pdf

As advised in ASX Trade Circular 2011/016, a new session state, Regulatory Halt (REG_HALT), will be introduced on 28 November. The REG_HALT session state will be used to refresh (via an auction) the ECR (Extreme Cancellation Range) Reference Price of an instrument where an instrument’s price limit threshold or recent traded prices approach or meet the ECR.