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
<property>
<name>max_subdom</name>
<type>int</type>
<writable-by>admin</writable-by>
<label>limit__max_subdom</label>
<extension>
<shared>false</shared>
</extension>
</property>
For details on limits, refer to the sections Supported Operations: Managing Client Accounts > Limits and Permissions , or Supported Operations: Managing Domain Accounts > Domain Settings > Limits, Permissions and Hosting Settings.