[[Apple ComputerInc.|Apple]]'s [[macOS|Mac OS X]] operating system uses a central window server (created entirely by Apple) that caches window graphics as [[Portable Document Format|PDF]], instead of storing and executing PostScript code{{Citation needed|date=February 2018}}. A graphics library called [[Quartz 2D]] provides PostScript-style imaging using the PDF rendering model (a subset, plus tweaks, of the PostScript model), but this is used by application frameworks—there is no PostScript present in the Mac OS X window server. Apple chose to use this model for a variety of reasons, including the avoidance of licensing fees for DPS and more efficient support of legacy [[Carbon (API)|Carbon]] and [[Classic (Mac OS X)|Classic]] code; [[QuickDraw]]-based applications use bitmapped drawing exclusively. Adobe's [[copyright]] stipulations{{citation needed|date=March 2021}} said by some to apply to the PDF standard are thereby purported to be much less restrictive, granting, it has been claimed (i.e., here, by a previous author) conditional copyright permission to anyone to use the format in software applications free of charge.{{citation needed|date=March 2021}}
