Excerpt from the docs:
All parent controls MUST contain a FormControl. The FormControl properties are persisted to a stream as specified in section 18.104.22.168. The name of this stream MUST be "f". An OleSiteConcrete is persisted in this stream for each embedded control, as specified by the FormControl in section 22.214.171.124. The FormControl can also contain a DesignExtender, as specified in section 126.96.36.199.
Specifies the structure, as persisted to a stream, of the type information of an embedded ActiveX control.
A bit field that specifies Boolean properties of a SiteClassInfo.
A bit field that specifies Boolean properties of a form.
A bit field that specifies the location of the scroll bars of a form.
Specifies the behavior of the TAB key in the last control of a form