Some Core Foundation services provide types and functions that are abstractions of things that have specific implementations on different operating systems. Code that makes use of these services is thus easier to port to different platforms.
Date and Number Services abstracts time utilities and offers facilities for converting between absolute and Gregorian measures of time. It also abstracts numeric values and provides facilities for converting between different internal representations of those values.
Several other services that abstract operating-system utilities are currently public on Mac OS X and in Cocoa for Windows but not on Mac OS 8 or Mac OS 9. Among these are inter-process notification and run-loop services.
Table 1 summarizes Core Foundation services.