According to the 2012 Annual Report and Accounts of OXXthe...

According to the 2012 Annual Report and Accounts of OXX
the issued capital was

152 million f.p. shares
74 million p.p. shares
33 million trustee shares issued pursuant to trustee stock scheme

It looks like the unlisted trustee shares could be sold off when more capital is required and then listed.

From the Report
"During the year, the members of Octanex voted to approve a new trustee stock scheme to replace the existing
such scheme and the Supreme Court of Victoria then gave its required approval to the new scheme at a hearing on
17 November 2010. As a consequence of the company obtaining those necessary approvals, the 33,000,000 trustee
shares held by the trustee under the then existing scheme were cancelled and 33,000,000 new trustee shares were
issued to the trustee under the new scheme. Those new trustee shares are unlisted and the trustee may sell those
shares as fully paid or partly paid ordinary shares and must then pass the net proceeds of their sale to the company"