Before computerisation a pink security transfer was utilized...

Before computerisation a pink security transfer was utilized when the transaction was made through the ASX using a stockbroker and a white standard transfer was made if a transaction was made between individuals (not using a stockbroker)
I would guess that this transaction is using the second option of a sale and advised to the ASX for recording purposes. Anybody can sell their stock independent of the ASX by using the secondary option by using a white transfer and then lodging the arrangement direct to the registry for the stock sold.