The tune.low, tune.med, and tune.high master files define the available ASET security levels. They specify the attributes of system files at each level and are used for comparison and reference purposes.
The uid_aliases file contains a list of multiple user accounts that share the same user ID (UID). Normally, ASET warns about such multiple user accounts because this practice lessens accountability. You can allow for exceptions to this rule by listing the exceptions in the uid_aliases file. ASET does not report entries in the passwd file with duplicate UIDs if these entries are specified in the uid_aliases file.
Avoid having multiple user accounts (password entries) share the same UID. You should consider other methods of achieving your objective. For example, if you intend for several users to share a set of permissions, you could create a group account. The sharing of UIDs should be your last resort, used only when absolutely necessary and when other methods will not accomplish your objectives.
The master files that are used by the systems files checks are generated when you first execute ASET, or when you run ASET after you change the security level.