Reference
PDF Format Reference A concise reference for PDF versions, the page tree, metadata and Base64 conversion.
A PDF is a header, a body of objects, a cross-reference table and a trailer. The trailer points at the catalog, whose page tree lists every page.
01 What lives where%PDF-x.y at the start states the version. The trailer names the /Root catalog and the optional /Info dictionary. The page tree under /Root lists the pages and their /MediaBox and /Rotate values. /Encrypt marks an encrypted document and /Linearized marks a linearized one. 02 Base64 is just an encodingBase64 does not change the document; it only represents the same bytes as text, with an optional data-URL prefix.
Limitations
A dependency-free reader reports a named limitation for compressed object or cross-reference streams instead of guessing values.
Frequently asked questions Does Base64 change the PDF? No. It is the same bytes in a text encoding; decoding restores the original file exactly. Why can't some metadata be read? When objects are stored in compressed streams, a dependency-free reader cannot inflate them and says so plainly. About the author Gampangin — Publisher and editorial team
Gampangin builds and maintains free, browser-based developer tools and the documentation that makes them trustworthy. The organization is accountable for every page published on this site.
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