I just googled and found out following:
Quote:
Originally Posted by Adobe PDF 101: Quick overview of PDF file format
The general structure of a PDF file is composed
of the following code components: header, body,
cross-reference (xref) table, and trailer......
The header contains just one line that identifies
the version of PDF.
The trailer contains pointers to the xref table and
to key objects contained in the trailer dictionary.
It ends with %%EOF to identify end of file.
The quote is taken from following link----->
LINK
Check out link above for more details about PDF file format.
HOPE THIS HELPS........
