Number of limits have values equal ot users of different access levels. For instance, mailbox quota is a shared parameter, because it's value is equal both for a client and for domain administrator. Graphically, the extension node can be represented in the following way:
The shared node is required. Data type: boolean.
Extension node sample
For details on limits, refer to the Limits and Permissions (client's settings), or Limits, Permissions and Hosting Settings (domain and domain administrator's settings) sections.