Best to contact the company if you are not sure but I understand...

Best to contact the company if you are not sure but I understand it in the simplest terms as this.

You can sell your shares in MGC back to the STP so long as they don't have any restrictions on them (e.g. you have borrowed against them). You cannot buy shares in MGC as it is winding up.

However you can still buy and sell units in the MGC Trust on the ASX still.

Shares and Units had the same economic value, shares just had the additional feature of voting rights on MGC as the cooperative.