In his blog Martin Bailey, CTO of Global Graphics and member of serveral ISO committees regarding PDF, describes the new halftone features of PDF 2.0 which is scheduled to the be published this year.
Calling screening spot functions is enhanced in PDF 2.0. In older versions one could only call names which are mentioned in the standard. Special spot shapes (e.g. for flexo printing) which are not available in all RIPs couldn’t be called just by it’s name. Now a PDF file can contain a list with multiple spot funktion names. The RIP is executing the first function recognized.
In addition the new standard support flexible screening definitions for transparent objects.