Window Bidirectional Attributes are assigned to each window in the Presentation Manager system. Window bidirectional attributes are usually inherited by a window, at creation time, from its parent window. This is true for all windows, except for windows that are children of the desktop window. These windows inherit their window bidirectional attributes from the process bidi attributes.
Applications use the WinSetLangInfo API with the LI_BD_WND_ATTR parameter to set specific window bidi attributes. Note that with the LI_BD_WND_ATTR applications have control on the way bidirectional attributes are inherited within the parent-child chain.
PM controls (which are part of the PM system) are sensitive to their bidirectional attributes. They determine their window layout based on the 'window orientation' attribute and perform text conversions based on other bidirectional attributes.