What a UDF file is, how to open it, and how to turn it into a PDF

UDF stands for UYAP Document Format. It is the format produced and read by the document editor built into UYAP, and court documents in Turkey are prepared in it: petitions, procedural orders, expert reports, interim decisions. When such a document is downloaded from a case file, it arrives with a .udf extension.

What you have is not a scan or an image. It is an editable text document with paragraphs, bold headings, numbered lists of claims, tables and sometimes embedded pictures. The difference from PDF is one of purpose: PDF is a publishing format that nearly every device can open, while UDF is a working format that needs software which specifically understands it.

Windows decides which program opens a file from its extension. If nothing on the machine is registered for .udf, either nothing happens or you get a "how do you want to open this file" dialog in which none of the listed programs helps. Adobe Reader, Word and your browser all decline it, simply because support for the format would have to be built in and it is not.

Renaming the file to .pdf or .doc does not help either: the contents stay the same and only the label changes, so those programs treat it as corrupt. The same limitation bites harder on a phone, since the official UYAP editor is desktop software — reading a UDF that landed in your inbox on a phone usually means converting it to PDF first.

Technically a UDF file is a compressed archive that holds a single XML file called content.xml. All of the document's text sits inside that XML in one continuous pool, in reading order: the header first, then the body, then the footer. Formatting is kept separately from the text — which stretch is bold, which point size it uses, how a paragraph is aligned, all recorded as entries pointing at a start position and a length in that pool.

One consequence of this is useful in an emergency. If you copy the file, change the copy's extension to .zip and open the archive, content.xml comes out and any text editor can display it. What you see is unformatted — alignment, tables and page structure are gone, and XML tags sit between the sentences — but it is enough to learn what the document says. Working on a copy keeps the original intact.

There is one more detail worth knowing: UDF does not store a laid-out page. Nothing in the file records where a line ends; the program that opens the document works that out itself. That is why the same document does not look pixel-for-pixel identical in two different programs.

The official route is installing the UYAP editor. It works, but it comes with an install, often with a Java dependency to sort out, and on a managed work computer possibly with an administrator approval you do not have. For someone who needs to read one document once, that is a lot of setup.

If you are counsel on the case, viewing the document through UYAP itself is usually possible. Clients, opposing parties and anyone receiving the file second-hand have no such access — which is precisely where the problem tends to start, once the document leaves the case file.

The route that needs no installation is converting the document to PDF. On Dosya Kalemi this is what the UDF to PDF tool does: the file is opened in your own browser and written out as a PDF, with nothing uploaded to a server. Since a UDF is usually case correspondence, that distinction matters — the document has no business passing through a third party. And before any of this, the simplest option is asking whoever sent it for a PDF, which they can produce from UYAP if they have access.

Kept: paragraph structure and alignment (left, centre, right and justified), bold, italic and underlined runs, differences in point size, text colour, indents, line spacing, the space above and below paragraphs, numbered and bulleted lists with the items of one list counted in order, the page breaks recorded in the document, tables with their column width proportions, merged cells, cell fill colours and borders, and PNG and JPEG images embedded in the document. First-line indents are preserved, and header and footer lines are written on every page in their own band, keeping the alignment they had in the document.

Dropped: the typeface itself. Times New Roman cannot be redistributed, so the output uses an openly licensed serif; because the letter widths differ, line breaks are recalculated and the distribution of text across pages can shift. Tab characters become a fixed-width gap rather than a real tab stop. A rare character the font has no glyph for becomes a space, and an embedded image in an unrecognised format is skipped — both so that one small defect does not cost you the whole document.

In short, the result is a readable, recognisable document: the full text, the emphasis, the list numbering and the tables are all there. It is not a facsimile, and it will not match the original screen for screen.

This is the most important point on the page. Most documents coming out of UYAP are electronically signed, and the signature is bound to the file itself rather than to how the document looks: separate signature data sits inside the archive, and verification is performed against the original file using that data.

A converter reads the text and formatting and writes a brand-new PDF from scratch. The signature data does not go into that new file, and putting it there would mean nothing anyway, since the signature would then stand against the contents of a file it never signed. The output is visually the same document, but its verifiability is lost along the way.

In practice: a converted PDF is fine for reading, for showing a client, for keeping in your own files and for passing the content on. It does not stand in for the original where a signed document is required. Keeping the UDF file itself and submitting that when a formal filing is needed is the safe course, and since different authorities accept different formats, asking the relevant office when in doubt is worth the trouble.