MIR 3.5.1

A Recognised Investment Exchanges shall, in relation to Financial Instruments traded on its systems, make public continuously throughout its normal trading hours, and submit to the Regulator, in accordance with the type of trading system they operate:
(a) the information specified in Rule 3.5.5; and
(b) current bid and offer prices and the depth of trading interests at those prices which are advertised through their systems.