Jean-Pierre,
I replied to the post you left in the Mac ATM and Type forum:
>Univers has a lot of weights with a very clever nomenclature system. In principle, you should never apply fake bold (or, as you call it, "bold attribute") to any font, but this is especially important in the case of the Univers family of type faces.
>
>If you need the "bold" version corresponding to Univers 57 (which is 'medium condensed') you need to select your text and apply Univers 67 to it. Univers 67 is 'demibold condensed' and, therefore, the "bold" version of Univers 57.
>
>For more on the naming system for the Univers family, check out this thread in the Typography forum:
Neil Keller "Univers family naming conventions" 3/1/04 9:27am