The intent of the CHECK option is to perform a test run informing you of possible error conditions and providing reports of SYSMOD status, libraries that will be updated, regression conditions, and SYSMODs that will be deleted. During CHECK processing, the list of distribution zone entries is maintained in storage; data is written to the distribution zone as a temporary storage medium. CHECK processing deletes any data written to the distribution zone. Consequently, no permanent updates are made to the distribution zone.