The numbering tab allows the configuration numbering rules that help ensure unique user names within Active Directory when creating new user accounts.
Determines the maximum number of variants of an account name to create. For example, a value of 4 with a SAM account name of "bjones<n>" would allow the generation of the following usernames
Determines the numeric width of the numeric values to use when generating usernames.
For example, a numeric width of one may generate the username "bjones1" whereas as value of two may generate the username "bjones01".
Include Base Account Name
Determines whether the account name without any numerical values should be generated before values are appended. When true in the previous example the user name "bjones" would be created before "bjones1", "bjones2" etc.