In normal circumstances, CVS works only with regular files. CVS also ignores file permissions and ownerships, leaving such issues to be resolved by the developer at installation time.
Files also lose their ownerships and permissions during repository transactions.
Using the PreservePermissions option affects the behavior of CVS in several ways. First, some of the new operations supported by CVS are not accessible to all users. In particular, file ownership and special file characteristics may only be changed by the superuser. The reason is that CVS's internal structure does not make it easy for these operations to collect all the necessary data about hard links, so they check for file conflicts with inaccurate data. Therefore, if only the permissions, ownership or hard linkage have changed, or if a device's major or minor numbers have changed, CVS will not notice.