How can i use android aaptOptions?

what are the meaning of the aaptOptions .noCompress , etc. Any body can explain them to me,Thank you.

aapt options

android {

aaptOptions {

noCompress ‘foo’, ‘bar’

ignoreAssetsPattern “!.svn:!.git:!.ds_store:!.scc:.:_:!CVS:!thumbs.db:!picasa.ini:!~”

}

}

This affects all tasks using aapt.