Checking Out a Component
The checkout component function copies a component from a baseline or promotion library into a staging library allocated exclusively to your package. If a package staging library has not already been created for the type of component you are checking out, a staging library for that type is allocated.
The checkout function can show you the baseline and promotion libraries that contain a component before you check it out. The display shows prior versions in baseline libraries as relative minus versions (-1, -2, -3). Future versions in promotion libraries are shown as plus (+) promotion level numbers (e.g. +10, +20, +30).