The new Illustrator CS from
Adobe can save files as PDF and can read PDF files. So far so good. But there are some problems.
Illustrator will save layer information in the PDF file, either in the same format as Illustrator 10 or in the new PDF 1.5 format.
But when you read the file back in, the layers are not recognised. Seems like a small bug.
When you use Illustrator to open PDF files you created with Illustrator, you might also get some errors like "unknown shading type".
Looks like Illustrator is not so good at reading its own files.
How can this happen?
I don't work at Adobe so i can only guess.
I assume they have separate teams for input and output of PDF.
PDF is not the native Illustrator format, so they need to convert.
I assume they have test files both for input and for output, but don't combine both in the same tests as this would cross team boundaries.
I wonder how many other software has this type of problems?