One approach was the VTK build system of 1999. That system consisted of a configure script for Unix and an executable called pcmaker for Windows. pcmaker was a C program that read in Unix Makefiles and created NMake files for Windows. The binary executable for pcmaker was checked into the VTK CVS system repository. Several common cases, like adding a new library, required changing that source and checking in a new binary. Although this was a unified system in some sense, it had many shortcomings