# UserCallback

This event allows the calling process to insert optional data into selected points of the HTML output. This event is triggered by the inclusion of the `$USERCB=``X` token in one of the properties, where `X` identifies the callback. The text in `szUserString` is inserted in the HTML. See $USERCB.

    UserCallback([in] BSTR szUserString,
                 [out, retval] BSTR *pszVal);

The `compsamp` sample program demonstrates how to use this event.

_FT_HTML5_bannerTitle.htm