I'm back

The last full entry I made to this blog was on January 28, 2008, almost 6 months ago. Even though I have been responding to comments and there is interesting information in them, it is really time that I get back to regular entries. I had a lot of distractions both professional and personal. Someone asked me if my blog was dead. My response was that it was in a coma and I would attempt to wake it up. Definitely still alive, just comatose.  So onward!

The ISO 32000-1 (PDF 1.7) specification got officially posted to the ISO website on July 2, 2008, just about 4 months after the final version was sent to them. It was all a done deal on January 24, 2008 when the committee approved the final edits to the specification. But it isn't real until it is real, and that happened on July 2.

You will find that you have to buy the specification from ISO and in the case of ISO 32000-1 the price is 370 CHF (Swiss Francs) the equivalent of about $360 US. Seems like a lot, but ISO has to finance itself somehow. With some luck, and based upon an agreement with ISO, Adobe will be posting a version of this document on our website for free but with references to the ISO copyright removed. The technical content and page numbering will be identical.

I thought it might be useful to cover in more detail some of the questions that came up as comments to my January 2008 post.

1)  Adobe's plan is to follow the ISO 32000-1 specification and not to pursue a direction for PDF competitive to the standard. ISO now owns the specification and Adobe supports that. However (isn't there always a however), Adobe products such as Acrobat and LiveCycle will be making extensions to ISO 32000-1. In fact, we have already done this for Acrobat 9.0.  Extensions, in general, are supported in PDF and ISO 32000-1 and the Acrobat team has documented the Acrobat 9.0 extensions and is submitting them to the ISO committee for consideration to be included in the next version of the standard, ISO 32000-2.  Annex E of ISO 32000-1 describes how extensions from developers are to be noted and documented. Adobe is following those rules.

PDF has been developed as versions (1.0, 1.1, ..., 1.7).  ISO 32000-1 is PDF 1.7 (same as the Adobe PDF 1.7) and the files are marked as such in the header line. Extensions to ISO 32000-1 are extensions to PDF 1.7. Since that PDF version cannot change, a different mechanism was introduced to allow developers to number their extensions and identify them with their developer prefix (Adobe’s prefix is "adbe"). So, Acrobat 9.0 supports PDF BaseVersion 1.7 (ISO 32000-1 version), (adbe) ExtensionLevel 3. The files that use new Acrobat 9 features are so marked with the new Extensions entry in the document catalog and as PDF 1.7 in the header line. Adobe's extensions are soon to be documented on our website. Other companies are free to use these Adobe extensions and they are also free to create and document their own extensions, properly marking the files with their extension numbers. Hopefully, this makes all the extensions public and useable by all.

2)  A lot of people have asked if the existence of ISO 32000-1 obviates the need for PDF/A (the archive subset of PDF).  The answer is a strong NO. PDF/A was created particularly for archiving documents and it both insists that certain PDF features are used (like structure which makes it easier to read PDFs to the blind and easier to extract the content into other formats) as well as insist that certain other features not be used to make sure that the document appearance is reliable (like not using JavaScripts or device dependent color spaces).  The fact that the full PDF is a standard does not impact those reasons for defining PDF/A. 

It could be that some organizations that must use public international standards were using PDF/A since PDF/A has been ISO 19005 since 2005. If they are using PDF/A strictly for that reason and not because of its archiving features, they may indeed want to use PDF 1.7 (ISO 32000-1) instead.

PDF/A is a strict subset of PDF 1.4 meaning that the files do not contain anything not defined for PDF 1.4.  Since PDF 1.4 is also a subset of PDF 1.7 and hence ISO 32000-1, all PDF/A files are good ISO 32000-1 files.

3) A PDF file that conforms to the ISO 32000-1 specification may contain a JPEG image, an ICC color space specification, XFA fill-out form information, an OpenType font and possibly many other kinds of material that are not directly specified in the ISO 32000-1 document (nor in the Adobe PDF 1.7 document).  There are, however, references in the ISO 32000-1 document to specifications for all of those subordinate standards that are used by PDF. Some of those specifications are themselves ISO standards (e.g., JPEG 2000) while others are documented in some other way. In all cases, they are publicly specified so that developers can read and understand every byte of a conforming PDF file. This was the way the Adobe managed PDF and ISO will continue to follow that path.

The way I choose to view this is that the "PDF standard" is documented in a tree of documents starting with the ISO 32000-1 document which references over 80 other specifications. Those, in turn, may make reference to yet other specifications. All of this information is needed to completely and totally understand what can be in a PDF file. So the ISO 32000-1 document and the standard, the way I define them, are different things. This came up in reference to the 3D representations now usable in PDF: U3D and PRC.  U3D is ECMA standard 363 and PRC is an Adobe open specification much like PDF used to be.  U3D is part of the PDF standard, not documented directly in the ISO 32000-1 document but included by reference. PRC is newer than the ISO 32000-1 document and so is documented and referenced, for now, as an Adobe extension.

It is good to be back!

Jim King  (contact me at:  jking@adobe.com)