4.0.2 function interface changed?

Greetings, Did something change in the way PHP functions have to be written between 4.0.1-pl2 and 4.0.2? I made a few personal modifications to the cpdf interface that worked fine under 4.0.1-pl2 but generate incorrect PDFs with 4.0.2. All I can think is that the calling convention or something of that nature changed. Is there a skeleton or sample of how functions _should_ be written for Zend and 4.0.2? The docs online are dated to 3.x and I have only seen brief descriptions here and there about 4.x conventions. I tried to look at other extensions for examples but there seems to be such a diverse use, is there any right way to do it? Thanks, Matthew