Q I really like Apple’s new San Francisco system font, and want to use it when editing text documents and messages in Mail. How come it is not listed in the fonts available, though?

A Apple’s new System Font, named San Francisco, was introduced with OS X 10.11 El Capitan, iOS 9, and watchOS 2.0. In doing so, Apple has stressed that it is only licensed for use by the System in displays, such as Finder windows.

San Francisco is perhaps the first font designed specifically for screen display on modern high-resolution systems. In constrast, the great majority of the other fonts which we use have been designed for printed output, and then tuned to work well on displays too. At present, Apple has no intention of supporting San Francisco’s use in printed output, so it is locked away for access by the operating system only.

This is accomplished by prefacing its name and ID with a period (.), so that its TrueType Unique ID record, for example, describes it as “.SF NS Text”, and it is explicitly identified as a System Font. This ensures that it is omitted from font selection menus and dialogs. The font itself is stored in files whose names start with SFNSText- in the /System/Library/Fonts folder.

As San Francisco does not exist on any other platform – even OS X Yosemite, for example – it would be most unwise to risk using it in anywhere outside an El Capitan or iOS 9 environment. As documents are inherently mobile, it would be bad news to use it in a document, as most who view that document would probably have another font substituted for it.

I know that this will disappoint many, as San Francisco has attracted quite a following since its release. Let’s hope that Apple tweaks it for print too, and perhaps allows its wider user then.