I think it was a regulatory halt because of the SP rise.
For info on REG_HALT see
Point 6 in https://www.asxonline.com/intradoc-cgi/groups/trading_and_market_information/documents/communications/asx_031976.pdf
and Point 2 in http://www.asx.com.au/resources/newsletters/companies_update/archive/CompaniesUpdate_20111123_0811_HTML.htm