After reading PDF file format specification manual and several other websites providing considerable amount of theories on this subject, I built one simple pdf file.
An empty blank page, pretty much doing nothing else. But my problem is, When I am trying to close it, Adobe Reader prompts a dialog for saving any changes. Its only happening with simple pdf files without any encoding/encryption.
For instance the following code,
1 0 obj <</Type /Catalog /Pages 2 0 R>>
2 0 obj <</Type /Pages /Kids [3 0 R] /Count 1>>
3 0 obj <</Type /Page /Parent 2 0 R /Resources <<>> /MediaBox [0 0 500 800]>>
0000000000 65535 f
0000000010 00000 n
0000000060 00000 n
0000000115 00000 n
trailer <</Size 4/Root 1 0 R>>
Another thing I noticed, in any PDF file after the PDF version, there are some bizarre set of characters, "%âãÏÓ" which is not mentioned in even Adobe PDF specification manual. But almost all PDFs I had in my collection has got this value, when I opened it using a hex editor.
Please shed some light on this topic, if any one knows. What is wrong with my pdf code and what is that strange set of bytes following pdf version