Ann: PSD Acquisition and Entitlement Offer - Presentation, page-52

Retail Entitlements which are not taken up by eligible retail shareholders by the close of the Retail Entitlement Offer and Entitlements that would otherwise have been offered to ineligible retail shareholders will be sold through the Retail Shortfall Book build on Thursday, 23 April 2015 ("Retail Shortfall Bookbuild”).
If the Retail Shortfall Bookbuild price exceeds the Offer Price, the difference between the two amounts will be paid (net of any withholding tax) to Eligible Retail Shareholders in respect of entitlements they did not take up and to Ineligible Retail Shareholders in respect of New Shares that would have represented their entitlements had they been eligible to participate in the Retail Entitlement Offer. There is no guarantee that there will be
any proceeds remitted to those retail shareholders.​

http://www.asx.com.au/asxpdf/20150330/pdf/42xl8qvshx0gwf.pdf​