Reembedding Fonts in a PDF

The FDA and other regulatory agencies have specific requirements regarding fonts used in drug applications. Notably, fonts need to be embedded for compliance

Ensuring that fonts are embedded properly is not particularly difficult if documents are in your control. See my blog article on PDF Settings  for some tips.

In a perfect world, all parties which contribute to a regulatory filing would properly embed fonts. Unfortunately, we don’t live in a perfect world . . . there are times when you may need to embed fonts as a post process.

Fortunately, a new feature of Acrobat 9 Pro (and Pro Extended) is the ability to reembed fonts.

Before we get into how to do that, you need to know if the fonts are there or not.

Are the fonts embedded?

To check if fonts are embedded:

  1. Choose File—> Properties
  2. Click on the Fonts tab

Examine the information in the window. If all font entries say "embedded" or "embedded subset" no changes are necessary:

Font is embedded

However, if you see an entry like the one below, you have a problem. In the case below, ArialMT is used in the document, but is not embedded.

Font is not embedded

In the remainder of this article, I’ll discuss how to reembed fonts and also provide background on the term "subset" relative to regulatory guidance.

Reembedding Fonts using Preflight in Acrobat 9

To reembed fonts in a PDF:

  1. Choose Advanced—> Preflight
  2. Expand the PDF fixups section
    Preflight window in Acrobat
  3. Choose the Embed Fonts fixup
    Embed font section
  4. Click Analyze and fix
Note: In order to reembed fonts, you must have the font available on your system. Not all fonts may be embedded. Some fonts have a "do not embed" flag which is a copyright restriction from the vendor of the font.

Font Substitution, Embedding and Subsetting

Font substitution in PDF will occur when the computer does not have access to the original font. If the original font is not present, an Adobe Multiple Master typeface is temporarily substituted for missing fonts— AdobeSerifMM for a serif fonts, and AdobeSansMM for sans serif fonts.

Documents submitted to technical review by the agency may contain formulas and other scientific characters. To prevent the possibility of a character being incorrectly substituted, documents must have fonts embedded.

Modern font sets often contain thousands of characters. Completely embedding a font greatly increases the file size of the resulting PDF. The solution is font subsetting. Subsetting only embeds the characters that are necessary to render the page. Visually, a document with subset fonts and completely embedded fonts looks and prints identically.

There is no technical advantage to completely embedding fonts. There is nothing you can do with a PDF that has its fonts completely embedded that you cannot do with a subset file.

In Acrobat 5 and earlier, combining subset files could sometimes lead to ballooning of file size. That’s not an issue today. Besides, the agency uses Acrobat 7 (or later I have heard in some cases) to review documents.

It has always been a mystery to us at Adobe as to why the agency requires completely embedding fonts in M2 eCTD: Electronic, Common Technical Document. Specification:

Agencies cannot guarantee the availability of any fonts except Times New Roman, Arial, and Courier and fonts supported in the Acrobat product set itself. Therefore, all additional fonts used in the PDF files should be embedded to ensure that those fonts would always be available to the reviewer. When embedding fonts, all characters for the font should be embedded, not just a subset of the fonts being used in the document

Only older Type 1 and TrueType fonts can be completely embedded by Acrobat. By the time the agency produced the guidance, the "writing was already on the wall" for the deprecation of Type 1 and TrueType fonts.

Adobe and Microsoft had jointly announced the OpenType format in the year 1996. OpenType is an interoperable superset/combination of Type 1 and TrueType fonts. Modern OSs such as Windows XP, Vista and Mac OSX ship with OpenType fonts. Adobe hasn’t sold Type 1 fonts in a number of years.

OpenType fonts are superior in a number of ways to older font technology:

  • Cross-platform format
  • Support multiple languages
  • Advanced typographic features and functions
  • Can contain up to 65,000 characters

Except for a few rare cases, Acrobat can only subset OpenType fonts.

So, where does that leave us? To my knowledge, the agency hasn’t rejected a filing with fonts that are subset. The M2 eCTD: Electronic, Common Technical Document. Specification document specifically allows subsetting of the large Asian font sets.

I am concerned that the agency does not insist that Times New Roman, Arial and Courier be embedded. While these fonts are commonly available on all systems, many versions of these fonts have been distributed over the years. While the differences are often subtle, I would be concerned that the character spacing could differ slightly.

My recommendation is that all fonts used in regulatory filings are embedded and subset.

Further Reading

Many of the articles below are several years old, but may be interesting from a historical perspective.

TrueType, PostScript Type 1, and OpenType: What’s the Difference (PDF)
This article by Adobe’s Tom Phinney provides a good historical background on the development of fonts over the last fifteen years.

OpenType initiative FAQ
An interesting historical document from the Microsoft website originally issued in 1996.

Type 1 (“PostScript”) to OpenType font conversion
Adobe document which describes issues associated with Adobe’s move from Type 1 to OpenType fonts.