Enhanced Metafile (EMF) Spooling is a capability incorporated in Windows 95 and NT. EMF spooling in effect stores printouts in a proprietary page description language. Microsoft describes the process as 'storing GDI calls rather than storing the bitmaps generated by the calls'. This often results in smaller print files and allows quicker return of control to applications when creating printouts as the creation of bitmaps can be deferred until the actual printing. (At least that's my interpretation of Microsoft's documentation which does not seem to distinguish clearly between generation and printing). EMF formatted files can, in concept, be rerouted to a different printer whereas raw files not in a description language like Postscript often can not.
In practice, EMF files may or may not be smaller than raw. They may be faster or may take longer to print. They may have different bugs than the equivalent raw file. The use of EMF spooling with Postscript or PCL printers is permitted, but is problematic. Microsoft recommends 'raw' format for Postscript and doesn't address PCL.
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Copyright 1994-2002 by Donald Kenney.