Setting compatibility mode of pdflib

Is there a way to set the compatiblilty mode to 1.2 using pdflib (I have a rip I want to send the native pdf file to, it will not accept a 1.3 version file.). As I am interpreting the documentation for both php and pdflib, the only way to get this to work is to issue: pdf_set_paramater($pdf, "compatibility", "1.2") before pdf_open(). There is no direct way to call pdf_new() or pdf_new2() in php, so the first time a handle to the pdf document can be established is upon calling pdf_open(). Can anyone help? TIA David