The Pro designation has absolutely nothing to do with the quality of the typeface or its suitability for use in “professional” work, but rather, designates (at least for the Adobe Type Library), typefaces with extended complements of glyphs and support for various OpenType font features. Such typefaces may support Eastern European languages via inclusion of Cyrillic and Greek glyphs) as well as lower case (a.k.a. “old style”) numerals, small caps, fractions, superscripts, subscripts, swash characters, extended ligatures, symbols, etc.
For the Adobe Type Library, a typeface is typically labelled Pro or Std (not a disease, but rather “standard”). For the case you cited, we do not offer Adobe Caslon in both Std and Pro versions, (Adobe does offer other “Caslon” font families sourced from other foundries, but they are not the same design as Adobe Caslon.) Note that the Pro typefaces are only available in OpenType format, not in the original Type 1 format. Further note that Adobe does still license the older Type 1 Adobe Caslon font family (including accompanying “expert” typefaces including small caps, lower case numerals, etc.), but we most strongly recommend that designers use the OpenType versions given the gradual withdrawal of support for Type 1 fonts by both Microsoft and Apple.
- Dov