I would say no, don’t capitalise roman as an adjective describing a typeface, unless of course you are an archaeologist and you dig up a Roman typeface. :)

>unless of course you are an archaeologist and you dig up a Roman typeface

A more recent example... http://www.gerardunger.com/fontstore/store-capitolium.html

However, when it’s a font name (noun rather than adjective), it may be capitalized.

But Capitoleum refers to its roman as Regular, rather than Roman — thereby avoiding the possibility of the font being a Roman roman. More of a Dutch Roman roman, really.

The Wikipedia article explains why “roman” is, in most typographic uses, spelt uncapitalized:
http://en.wikipedia.org/wiki/Roman_type

Wiki says no, but can you really trust an open-forum encyclopedia?

If you mean the Wikipedia article “roman type”, yes, you can trust that particular article. I wrote and researched it using the best type history sources available. A novice Wikipedian calling himself an “amateur linguist” recently tried to remove the statement about Renaissance and later roman lettering versus ancient Roman lettering on the grounds that he thought it sounded like original research. He was out of his depth. I advised if he had trouble believing the statement as the published opinion of major type historians he should find a copy of the source I used and verify it for himself.

In general, Wikipedia cannot be trusted unless the content you’re reading is cited with a verifiable reference. Wikipedia is a crank magnet.

j a m e s

>A novice Wikipedian calling himself an

You should have reported him to the “Jedi council”.

...so the same for “roman numerals”?

No, “Roman numerals” is still capitalized. (A dictionary is all you really need for either question.)

No, “Roman numerals” is still capitalized. (A dictionary is all you really need for either question.)

The dictionary is wrong, illiterate, uninformed and out of its depth.

j a m e s

The dictionary is wrong, illiterate, uninformed and out of its depth.
Roman numerals are those as used by Romans. Ergo it is capitalised because it refers to the specific Roman culture as is per the norm in English. But roman numerals would be contrasted with italic numerals. Hence also Arabic numerals, but arabic alphabet (in general) yet Arabic alphabet (when denoting specifically the Arabic language).

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