What were AFM font files for?

[elmimmo]

Considering that Adobe Font Folio provides and AFAIK always provided PostScript Type 1 fonts, in its Mac version, with outline files + a suitcase file per family that supposedly included the font metrics in its resource fork, and in its Windows versions, with PFB outline files + PFM metrics files, what were AFM file ever intended for? Why did Adobe also include those? What were their purported use case? As a matter of fact, wasn't every other foundry providing PostScript Type 1 fonts in the same way? In what case would one ever need those AFM files for, even back in the day?

[elmimmo]

Note that I have searched and found the thread Re: Do we really need .AFM files anymore in OS X?‌, but while it does say that those are pretty much useless now, it does not clear up if they were ever useful for anything in the first place.

[Dov Isaacs · Accepted solution]

Back in the day, there were applications that used the .afm files to obtain metrics beyond those put into the .pfm files on Windows or the so-called screen fonts on the Mac. And for that matter, there were also applications that ran on raw MS-DOS and/or UNIX that didn't support the other metrics mechanisms.

Also, ATM (Adobe Type Manager, not the cash machine) had the capability of creating .pfm files from a combination of the .pfb file and corresponding .inf and .afm files delivered in the early font packages which often did not have a .pfm file.

Obviously, with OpenType fonts, the need for all those other files has gone away.

       - Dov

[elmimmo]

Thanks for the heads up. One forgets that back in the day there were things beyond Mac and Windows ^_^.

If their purpose was providing compatibility with environments were ATM was not available, I still don't quite understand what AFM files were included for particularly in the Mac version of Font Folio. Considering that Mac fonts relied on resource forks, unsupported AFAIK in anything but Mac OS, the outline files were non-portable to other operating systems without a sorts of conversion anyway. So if one was expected to have to convert the outlines files in order to port them to other systems anyway, why not being expected to convert the metrics and metadata inside Suitcase files too? It's not like AFM files saved you of having to do a conversion.

[Dov Isaacs]

There were older versions of MacOS applications that in fact did look at those files, which ones, I've really forgotten after 25 years here at Adobe!

         - Dov