| **Navigation:**  [[introduction.htm|Language Reference]] > App A - DDE, OLE, and OCX > OLE (.OCX) Custom Controls >====== OLE custom control Overview ====== | [[ole   ocx  custom controls.htm|{{btn_prev_n.gif|Previous page}}]][[introduction.htm|{{btn_home_n.gif|Return to chapter overview}}]][[ ocx control properties.htm|{{btn_next_n.gif|Next page}}]] |
|  ||

OLE custom controls commonly have the .OCX file extension. Therefore, they are commonly referred to as OCX controls are built to Microsoft's OLE 2 specification, which was designed with cross-language compatibility in mind.