The following three attributes are cached with a window, when the  
window is created.  
    
      
      
     
 
 MPI_WIN_BASEwindow base address.  
 
 
 MPI_WIN_SIZE window size, in bytes.  
 
 
 MPI_WIN_DISP_UNITdisplacement unit associated with the  
window.  
 
  
 
In C, calls to  
 MPI_Win_get_attr(win, MPI_WIN_BASE, &base, &flag),   
  
 MPI_Win_get_attr(win, MPI_WIN_SIZE, &size, &flag) and  
  
 MPI_Win_get_attr(win, MPI_WIN_DISP_UNIT, &disp_unit, &flag)  
will return in  base a pointer to the start of the window  
 win, and will return in  size and  disp_unit  
pointers to the size and displacement unit of the window,  
respectively.  And similarly, in C++.  
 
In Fortran, calls to  MPI_WIN_GET_ATTR(win, MPI_WIN_BASE,  
base, flag, ierror),  
  
 MPI_WIN_GET_ATTR(win, MPI_WIN_SIZE, size, flag, ierror) and  
  
 MPI_WIN_GET_ATTR(win, MPI_WIN_DISP_UNIT, disp_unit,  
flag, ierror)  
will return in  base, size and  disp_unit the  
(integer representation of) the base address, the  
size and the displacement unit of the window  win, respectively.  
(The window attribute access functions are defined in  
Section New Attribute Caching Functions 
.)  
The other ``window attribute,'' namely the group of processes attached to the window, can be retrieved using the call below.
| MPI_WIN_GET_GROUP(win, group) | |
| IN win | window object (handle) | 
| OUT group | group of processes which share access to the window (handle) | 
 
  int MPI_Win_get_group(MPI_Win win, MPI_Group *group) 
  
  MPI_WIN_GET_GROUP(WIN, GROUP, IERROR)
 INTEGER WIN, GROUP, IERROR 
  
  MPI::Group MPI::Win::Get_group() const 
  
  
MPI_WIN_GET_GROUP returns a duplicate of the group of the communicator used to create the window. associated with win. The group is returned in group.