Scripts determine the specific behavior of a build job. For example, you can define a script to do any of the following:
compile and link
clean up the build area before the build executes
rename files that have been transferred into the build area, before the build executes
delete temporary files after the build executes
Scripts can be defined at a build configuration level or a target level. (Target-level scripts are known as transition scripts.) There are important differences between the two.