Used to initiate an action, such as a product-specific function, or block-to-block navigation.
Only use buttons for the most commonly needed functions in a form. Put other functions in the Special menus.
Try to use only one row of buttons per window. (OMS-74239)
Provide one default button per window, where that function is the most likely for the user to perform. Always provide a default button in a modal window (typically "OK"). (OMS-74039)
Sequence buttons within a window as follows:

Place the default button to the left of all other buttons.
Place the Cancel button immediately to the right of the default button to form a group.
Place all other buttons in a group to the right.
EXCEPTIONS:
If the Cancel button is the default button, do not reposition it within its group.
In cases where there are other actions which are logically related to the default button, place those buttons immediately to the right of the default button. Place the Cancel button in the rightmost position of the group.
Follow the same button sequence rules for modal windows except when the modal window includes a Help button. Place the Help button in the leftmost position.

Buttons within a window should be sized similarly and spaced consistently, except when using gaps to group related buttons. If a window contains one button with a particularly long label, but all the other buttons have short labels, only size the short-labeled buttons the same.
Buttons may be placed on tab regions if they only apply to the contents of that specific region.
The default button should never be placed in a tab region where it can be accessed by keystroke when not visible.
The right edge of the rightmost button must be 0.1" from the right edge of the window. In general, leave 0.1" between buttons. If there are logical groupings of buttons, leave 0.5" between the groups (and still place 0.1" between the buttons in each group). If horizontal space does not allow 0.5" between groups of buttons, then leave as much separation as is possible. (OMS-74041)
[Translation] A button has a minimum width of 0.2" just to support the cosmetics of the widget. To adhere to translation requirements, the actual minimum width of a button is therefore 1.2." See the section on Text for more information on expansion requirements for button labels. (OMS-74042)
See: Text
In general, buttons are navigable except for the following: (OMS-76013):
Buttons below a multi-record block
Buttons that only apply when the cursor is in a particular field
The "Clear" button in a Find window
All buttons have an access key except "OK" and "Cancel" within dialog windows. "OK" must have an access key if it is not the default button, and "Cancel" must have an access key if it does not perform the same function as "Close Window."(OMS-74043)
All but the simplest modal windows should have a Help button in the lower left corner.
All iconic buttons must provide Tooltip text.
Textual Buttons are displayed as follows (OMS-74044):
Height: 0.3"
Rounding: Buttons that have the same Y-coordinate, and are spaced within 30 pixels of each other, have only their outermost edge rounded. A button with no other button near to it has both edges rounded.
Iconic buttons within a screen are either 0.25" by 0.25" or 0.3" by 0.3."
For information on implementing Buttons, see the Oracle Applications Developer's Guide.