5 ms·

I'm thankful PDF won, because otherwise I think it would have been Microsoft Word. There was a time when papers, books, resumes, contracts, etc. almost always c

I'm thankful PDF won, because otherwise I think it would have been Microsoft Word. There was a time when papers, books, resumes, contracts, etc. almost always came as Word. Does anyone else remember getting a book as preface.doc, chap1.doc, chap1a.doc, chap2.doc, subchap2a2.doc, and so on, and a mess of jpegs and gifs and trying to figure out how it had to be assembled, and discovering something was missing, or that one chapter was newer than the others. That's one reason I really like PDF -- it's one file, self-contained, and linear. On the other hand, I really wish it was more diff'able. If for example a credit card company changes one word in their terms & conditions PDF, it seems like 90% of document changes at the binary level. I know that PDF diff tools exist, but there must be tremendous internal complexity in the PDF format for tiny changes to alter the whole structure.

deleted 6y ago
[deleted]
rahimnathwani 6y ago
"but there must be tremendous internal complexity in the PDF format for tiny changes to alter the whole structure." Imagine a simple file format that doesn't support text wrapping, but allows you to specify elements as (x, y, s) where (x, y) specify a position, and s is a string that will be written left-to-right, truncated at the edge of the screen. That's a simple file format, right? But inserting a word somewhere early in that document would change the string within every element in the rest of the paragraph. And maybe move the y position of every element later in the document. That would be a PITA to diff. Even more so if the document has more than one column.
ternaryoperator 6y ago
>I'm thankful PDF won, because otherwise I think it would have been Microsoft Word. Well, probably Microsoft XPS, which was actually a fairly well designed format. But Microsoft didn't have the fight in them to really push it as a competitor to PDF. In part, I suspect b/c it's hard to justify investing a lot of money in your competing document standard as there is not much revenue you can derive from it. As of 2018, Microsoft no longer bundles XPS support in Windows 10.
- tonyedgecombe 6y ago
  Interestingly it still exists inside the print spooler, it's the default spool format for modern printer drivers.
- ksec 6y ago
  XPS happened during the Microsoft era, which means no one really wants another format dictated by them. So there was very little incentives, interest and adoption. XPS ultimately became an Open Standard as Open XML Paper Specification. But the fear and burn during IE era were far too great.
- webreac 6y ago
  They had also RTF which was one of the best formats created by Microsoft.
  - vram22 6y ago
    I don't have an opinion on how good a format RTF is, but I kind of like it. As part of a Java project (a while ago), I studied the RTF format, partly by reading the spec, and partly through reverse engineering - by creating multiple incrementally larger RTF docs, starting from zero content, then adding a word, then a font style, then a paragraph, a table, etc. And after each addition, opened the RTF in a hex editor and viewed the content, to help decipher the format rules. Then wrote a small RTF generation library in Java, that we used in the project to programmatically generate reports from DB data fetched via EJB. I also provided some ability to vary content and style independently. Good fun.
    - einpoklum 6y ago
      In what ways is it preferable to ODT (OpenDocument format)?
      - sidpatil 6y ago
        RTF is a much simpler format than ODT. RTF source code resembles TeX at first glance; ODT is based on XML. Unfortunately, it's not an open standard AFAICT.
axiolite 6y ago
> If for example a credit card company changes one word in their terms & conditions PDF, it seems like 90% of document changes at the binary level. Convert to text with: pdftotext -layout
marcan_42 6y ago
PDF objects within the file are usually compressed. That means if anything changes, the whole compressed binary blob changes. Other than compression and such encodings, PDF files are actually text files, with a drawing model largely based on PostScript but without the programming. If you want to diff them, use `mutool clean -d -a` to first turn them into pure ASCII text. That said, since it's a "baked" layout format, if one word pushes the rest of the text forward, everything after that will show up with changed coordinates. It's closer to a vector image format like SVG than a markup format like HTML or ODF. There are also things like font subsetting, where removing a word that was the only use of a character, or adding a word that uses a new character, might change the font data to add/remove those characters.
- deleted 6y ago
  [deleted]
tonyedgecombe 6y ago
The main thing for me is I don't need the originating application or fonts. I have twenty year old PDF files created by some long gone software that I can still read.
yyyk 6y ago
We'd probably be using PostScript and maybe later XPS. Word never had a print-oriented format with exact layout.
pjmlp 6y ago
The irony is when I get told that people want an application to output PDF instead of Word, because it is read only. I always get amused by proving those people how to edit PDFs. It is the same logic that documents sent by Fax are legally binding but the same document sent by email not.
- Closi 6y ago
  As someone that does this, it’s because they are harder to change for the average user, and that barrier also means ‘don’t do it’ in a soft sense. If I send a PPT you are almost saying to a client “you can edit this if you want, because I provided it in a format which is designed for editing rather than a format that was designed for view-only”. 99% of the time it stops the “Oh great, so when you took that presentation we prepared for you as a consultancy, you kept our logo on it but changed the content and also removed our caveats!” Also it stops people seeing my personal notes and comments that I have included throughout the document if it’s a ppt, and it also stops me sharing the data behind any graphs which is normally internally stored in the ppt file. You can set a ppt as view only, but nobody does it and clients don’t like it.
  - Cancan82 6y ago
    Yes - the dangers of sending a PPT to someone are real... your theme, your logo, someone else’s words. Unless a person is setup specifically to edit PDFs, there are limited tools to do so. Change to many words and spacing and alignment gets off. And it’s annoying.
- bane 6y ago
  Wait until you get a PDF which is just a bunch of poorly scanned JPGs and no OCR.
  - pjmlp 6y ago
    That is why one pays for Adobe Acrobat.
- dharmab 6y ago
rstuart4133 6y ago
I don't know of a better alternative to PDF that was around at the time, but I can't say I'm a fan. It undeniably works well as a way of placing pixels precisely on a page but then so does PNG, and PNG is far simpler and compresses better for computer generated content. Sadly some information I only get as PDF's, so I have to scrape them. Easy right? It can be, if the PDF is structured sanely. But PDF isn't some well defined data structure for laying out the page, it's a Turing complete stack based computer program that can do whatever it damned well pleases. The font tables don't necessarily have ' '=32, 'A'=65, 'a'=97. Why not optimise it and get rid of all those gaps, so now ' '=0, 'A'=30? And it doesn't have to be drawn in any sane order. It can be just a mess that makes even copy & paste near impossible, and some are. Did we really need to invent a DSL that has to be executed every time we wanted to view page? I remember it being pushed as a cool solution at the time. It doesn't look so cool now. SVG would be an improvement.
- saagarjha 6y ago
  PNG is of course an image format, and that means it doesn't really do text well. (Oh, and PDF is fully Turing complete and can even execute JavaScript, to in some contexts calling it a DSL is straining the definition a bit.)
- yyyk 6y ago
  PNG doesn't support multiple pages and didn't supplant GIF until 2000 or so. TIFF does, but in practice it's always uncompressed (did it even support compression in the 90s?). Either solution didn't allow for text blocks or vector zooming or form fields. It's not difficult to improve upon a sane subset of PDF, but that would require backing and coordination. Reviving XPS (but not under MS auspices) should also be possible.
einpoklum 6y ago
> because otherwise I think it would have been Microsoft Word. No, those are formats with completely different scopes. They don't compete and are essentially non-interchangeable. > There was a time when papers, books, resumes, contracts, etc. almost always came as Word. There was never such a time. I mean, sure, you could (and can) send people Word/LibreOffice documents, but things that needed some reproducibility and finality [1] were distributed or published is MS-Word format - almost ever. Postscript used to be pretty popular though. [1] - Yes, PDFs can be edited too, I know.
redman25 6y ago
PDFs act more like images than text. I made a tool for diffing PDFs at the visual level a little while ago (http://parepdf.com http://parepdf.com) because I needed a way to see the explicit differences between PDFs. Diffing PDFs at the textual level is a much harder problem though since lines of text need to be reordered and concatenated with each other. Unfortunately there is nothing built into the format that allows you to know what line belongs with what other line beyond guesswork.
- daltonlp 6y ago
  That's a very nice tool! I attempted something similar (https://nicediff.com https://nicediff.com), and found the textual approach to be basically useless: Tax form example: https://www.nicediff.com/view/7a5f41ba3c76ae9bb45f42a4faa8b6ad0bf2d95c https://www.nicediff.com/view/7a5f41ba3c76ae9bb45f42a4faa8b6...

deleted 6y ago

[deleted]

rahimnathwani 6y ago

"but there must be tremendous internal complexity in the PDF format for tiny changes to alter the whole structure." Imagine a simple file format that doesn't support text wrapping, but allows you to specify elements as (x, y, s) where (x, y) specify a position, and s is a string that will be written left-to-right, truncated at the edge of the screen. That's a simple file format, right? But inserting a word somewhere early in that document would change the string within every element in the rest of the paragraph. And maybe move the y position of every element later in the document. That would be a PITA to diff. Even more so if the document has more than one column.

ternaryoperator 6y ago

>I'm thankful PDF won, because otherwise I think it would have been Microsoft Word. Well, probably Microsoft XPS, which was actually a fairly well designed format. But Microsoft didn't have the fight in them to really push it as a competitor to PDF. In part, I suspect b/c it's hard to justify investing a lot of money in your competing document standard as there is not much revenue you can derive from it. As of 2018, Microsoft no longer bundles XPS support in Windows 10.

tonyedgecombe 6y ago
Interestingly it still exists inside the print spooler, it's the default spool format for modern printer drivers.
ksec 6y ago
XPS happened during the Microsoft era, which means no one really wants another format dictated by them. So there was very little incentives, interest and adoption. XPS ultimately became an Open Standard as Open XML Paper Specification. But the fear and burn during IE era were far too great.
webreac 6y ago
They had also RTF which was one of the best formats created by Microsoft.
- vram22 6y ago
  I don't have an opinion on how good a format RTF is, but I kind of like it. As part of a Java project (a while ago), I studied the RTF format, partly by reading the spec, and partly through reverse engineering - by creating multiple incrementally larger RTF docs, starting from zero content, then adding a word, then a font style, then a paragraph, a table, etc. And after each addition, opened the RTF in a hex editor and viewed the content, to help decipher the format rules. Then wrote a small RTF generation library in Java, that we used in the project to programmatically generate reports from DB data fetched via EJB. I also provided some ability to vary content and style independently. Good fun.
  - einpoklum 6y ago
    In what ways is it preferable to ODT (OpenDocument format)?
    - sidpatil 6y ago
      RTF is a much simpler format than ODT. RTF source code resembles TeX at first glance; ODT is based on XML. Unfortunately, it's not an open standard AFAICT.

axiolite 6y ago

> If for example a credit card company changes one word in their terms & conditions PDF, it seems like 90% of document changes at the binary level. Convert to text with: pdftotext -layout

marcan_42 6y ago

PDF objects within the file are usually compressed. That means if anything changes, the whole compressed binary blob changes. Other than compression and such encodings, PDF files are actually text files, with a drawing model largely based on PostScript but without the programming. If you want to diff them, use `mutool clean -d -a` to first turn them into pure ASCII text. That said, since it's a "baked" layout format, if one word pushes the rest of the text forward, everything after that will show up with changed coordinates. It's closer to a vector image format like SVG than a markup format like HTML or ODF. There are also things like font subsetting, where removing a word that was the only use of a character, or adding a word that uses a new character, might change the font data to add/remove those characters.

deleted 6y ago
[deleted]

tonyedgecombe 6y ago

The main thing for me is I don't need the originating application or fonts. I have twenty year old PDF files created by some long gone software that I can still read.

yyyk 6y ago

We'd probably be using PostScript and maybe later XPS. Word never had a print-oriented format with exact layout.

pjmlp 6y ago

The irony is when I get told that people want an application to output PDF instead of Word, because it is read only. I always get amused by proving those people how to edit PDFs. It is the same logic that documents sent by Fax are legally binding but the same document sent by email not.

Closi 6y ago
As someone that does this, it’s because they are harder to change for the average user, and that barrier also means ‘don’t do it’ in a soft sense. If I send a PPT you are almost saying to a client “you can edit this if you want, because I provided it in a format which is designed for editing rather than a format that was designed for view-only”. 99% of the time it stops the “Oh great, so when you took that presentation we prepared for you as a consultancy, you kept our logo on it but changed the content and also removed our caveats!” Also it stops people seeing my personal notes and comments that I have included throughout the document if it’s a ppt, and it also stops me sharing the data behind any graphs which is normally internally stored in the ppt file. You can set a ppt as view only, but nobody does it and clients don’t like it.
- Cancan82 6y ago
  Yes - the dangers of sending a PPT to someone are real... your theme, your logo, someone else’s words. Unless a person is setup specifically to edit PDFs, there are limited tools to do so. Change to many words and spacing and alignment gets off. And it’s annoying.
bane 6y ago
Wait until you get a PDF which is just a bunch of poorly scanned JPGs and no OCR.
- pjmlp 6y ago
  That is why one pays for Adobe Acrobat.
dharmab 6y ago

rstuart4133 6y ago

I don't know of a better alternative to PDF that was around at the time, but I can't say I'm a fan. It undeniably works well as a way of placing pixels precisely on a page but then so does PNG, and PNG is far simpler and compresses better for computer generated content. Sadly some information I only get as PDF's, so I have to scrape them. Easy right? It can be, if the PDF is structured sanely. But PDF isn't some well defined data structure for laying out the page, it's a Turing complete stack based computer program that can do whatever it damned well pleases. The font tables don't necessarily have ' '=32, 'A'=65, 'a'=97. Why not optimise it and get rid of all those gaps, so now ' '=0, 'A'=30? And it doesn't have to be drawn in any sane order. It can be just a mess that makes even copy & paste near impossible, and some are. Did we really need to invent a DSL that has to be executed every time we wanted to view page? I remember it being pushed as a cool solution at the time. It doesn't look so cool now. SVG would be an improvement.

saagarjha 6y ago
PNG is of course an image format, and that means it doesn't really do text well. (Oh, and PDF is fully Turing complete and can even execute JavaScript, to in some contexts calling it a DSL is straining the definition a bit.)
yyyk 6y ago
PNG doesn't support multiple pages and didn't supplant GIF until 2000 or so. TIFF does, but in practice it's always uncompressed (did it even support compression in the 90s?). Either solution didn't allow for text blocks or vector zooming or form fields. It's not difficult to improve upon a sane subset of PDF, but that would require backing and coordination. Reviving XPS (but not under MS auspices) should also be possible.

einpoklum 6y ago

> because otherwise I think it would have been Microsoft Word. No, those are formats with completely different scopes. They don't compete and are essentially non-interchangeable. > There was a time when papers, books, resumes, contracts, etc. almost always came as Word. There was never such a time. I mean, sure, you could (and can) send people Word/LibreOffice documents, but things that needed some reproducibility and finality [1] were distributed or published is MS-Word format - almost ever. Postscript used to be pretty popular though. [1] - Yes, PDFs can be edited too, I know.

redman25 6y ago

PDFs act more like images than text. I made a tool for diffing PDFs at the visual level a little while ago (http://parepdf.com http://parepdf.com) because I needed a way to see the explicit differences between PDFs. Diffing PDFs at the textual level is a much harder problem though since lines of text need to be reordered and concatenated with each other. Unfortunately there is nothing built into the format that allows you to know what line belongs with what other line beyond guesswork.

daltonlp 6y ago
That's a very nice tool! I attempted something similar (https://nicediff.com https://nicediff.com), and found the textual approach to be basically useless: Tax form example: https://www.nicediff.com/view/7a5f41ba3c76ae9bb45f42a4faa8b6ad0bf2d95c https://www.nicediff.com/view/7a5f41ba3c76ae9bb45f42a4faa8b6...