My contributions to the design of PDF:

• Co-designed the overlay of XML-like logical structure on the page-display oriented language (with Bennett Leeds). [See the PDF Reference, starting at page 784 (9 MB; opens to the page in some browsers).]
• Determined how to embed metadata expressed via the Adobe Extensible Metadata Platform (XMP) into PDF. [See the PDF Reference, starting at page 773.]

I am honored to be listed as a one of about 40 Key Contributors to the PDF language. [You can view the list on page 1213 of the PDF 1.6 manual; the PDF 1.7 manual no longer includes the list.]

Modifying the definition of PDF at Adobe is not a light matter: it requires review by a committee of stern wizards representing all the products that rely on the language as well as the interests of the company as steward of the language. Proposals have to satisfy a real need, must be backed by implementation, and must not break compatibility with earlier versions of the language.

Some of my contributions to Adobe Acrobat:

• Got Acrobat external editing working. This feature lets you edit an image in a PDF document in an external application such as Adobe Photoshop.
• Integrated handling of XMP metadata into Acrobat. Acrobat 5.0 was the first application to implement XMP.
• Fixed up the code that concatenates two PDF documents together, and added a lot of handling for PDF Logical Structure and bookmarks and other things that have to be merged. This code gets used a lot from many different parts of Acrobat.
• Designed the special pdfmark codes in PostScript that tell Acrobat Distiller how to create PDF Logical Structure in its output. Adobe FrameMaker uses this interface.
• Co-implemented the Logical Structure programming interface for Acrobat plugins and PDF Library clients to use. Adobe InDesign uses this interface.