You can save both audio and software instrument regions as Apple Loops in Logic Pro. For audio regions, a default set of transients—based on the project’s tempo information—is automatically created.

You use the Apple Loops creation utilities available in Logic Pro to create any of the following files: an Apple Loops file based on an audio file that matches the project tempo, a Software Instrument Apple Loops (SIAL) file, or a nonlooped Apple Loops file based on an audio file that does not match the project tempo. Nonlooping Apple Loops (or one-shots) do not follow the project tempo and key. This is useful if you want to add discrete, nonmusical sounds (such as sound effects) to the loop library, which should not be altered by the tempo and key properties.