BSTR m_bstrCaption;
Remarks
The data member in your control class that holds text to be displayed with the control. If you choose the CAPTION option from the Stock Properties tab in the ATL Object Wizard, the wizard automatically creates this data member in your control class, creates put and get methods for the property, and supports IPropertyNotifySink to automatically notify the container when the property changes.
CComControl Overview | Class Members
See Also CComControl::m_bstrText