Value 

Meaning 

poDesigned  

The form appears positioned on the screen and with the same height and width as it had at design time.  

poDefault  

The form appears in a position on the screen and with a height and width determined by the operating system. Each time you run the application, the form moves slightly down and to the right. The right side of the form is always near the far right side of the screen, and the bottom of the form is always near the bottom of the screen, regardless of the screen's resolution.
The operating system only supports this for overlapped windows. For a pop-up or child window (that has a BorderStyle of bsDialog or bsNone, for example), the window is positioned in the upper left corner of the screen.  

poDefaultPosOnly  

The form displays with the size you created it at design time, but the operating system chooses its position on the screen. Each time you run the application, the form moves slightly down and to the right. When the form can no longer move down and to the right and keep the same size while remaining entirely visible on the screen, the form displays at the top-left corner of the screen.
The operating system only supports this for overlapped windows. For a pop-up or child window (that has a BorderStyle of bsDialog or bsNone, for example), the window is positioned in the upper left corner of the screen.  

poDefaultSizeOnly  

The form appears in the position you left it at design time, but the operating system chooses its size. The right side of the form is always near the far right side of the screen, and the bottom of the form is always near the bottom of the screen, regardless of the screen's resolution.  

poScreenCenter  

The form remains the size you left it at design time, but is positioned in the center of the screen. In multi-monitor applications, the form may be moved from this center position so that it falls entirely on one monitor, as specified by the DefaultMonitor property.  

poDesktopCenter  

The form remains the size you left it at design time, but is positioned in the center of the screen. No adjustments are made for multi-monitor applications.  

poMainFormCenter  

The form remains the size you left it at design time, but is positioned in the center of the application's main form. No adjustments are made for multi-monitor applications. This position should only be used with secondary forms. If set for a main form, it acts like poScreenCenter.  

poOwnerFormCenter  

The form remains the size you left it at design time, but is positioned in the center of the form specified by the Owner property. If the Owner property does not specify a form, this position acts like poMainFormCenter.