With all the features of the Standard version and then some, Acrobat 6.0 Professional is a dream come true for graphic artists and prepress pros. But it may leave its secondary market, engineers and architects, stranded by the side of the road.

Most significant for prepress folks is Acrobat 6.0 Professional's ability to output in PDF/X-1a and PDF/X-3 formats, ISO-standard versions that are more restrictive -- and hence more predictable and dependable -- than other PDF flavors. Moreover, you can preflight your PDF files within Acrobat. Many customizable preflighting scripts are built in, including several for PDF/X.

Another crucial output feature is the PDF Optimizer tool, which can resample graphics, adjust font-subsetting specs, and remove possibly unwanted content, such as JavaScripts, external links, and thumb-nails. It can also optimize files for faster Web display. But it would be more useful if you could save PDF Optimizer settings for future use.

Acrobat 6.0 uses PDF 1.5, so for the short term you should save PDF files in Acrobat 5.0 format to ensure compatibility with older systems.

Acrobat 6.0 Professional can output color separations. It can also take direct control of PostScript output devices to add features, including registration and bleed marks and color bars. Version 6.0's new measuring tools, grids, and guidelines give you precision control over page geometry. You can zoom in to 6,400 percent to examine minute attributes, such as precise alignments.

Acrobat continues to be a good choice for engineers and architects who want to share CAD files and other technical drawings. But the Professional version doesn't offer many additional features for these technical pros.

Only users of the Windows-only Microsoft Visio and Autodesk's AutoCAD get one-button PDF creation with layer preservation (Mac users can view and comment on these files, layers intact, with Standard). Of course, we'd like to see PDF file-creation with layers for Mac-based design tools, such as Nemetschek's VectorWorks and Graphisoft's ArchiCAD.

Macworld's Buying Advice

For architects and engineers, the Standard version is enough: Acrobat 6.0 Professional's additional features aren't worth $150 more. But prepress professionals should upgrade to the Pro version. It offers the control they've been waiting for.