The EM_SETPARAFORMAT message sets the paragraph formatting for the current selection in a rich edit control.
EM_SETPARAFORMAT 
wParam = 0;  // not used; must be zero 
lParam = (LPARAM) (PARAFORMAT FAR *) lpFmt; 
 Rich Edit 2.0 and later: This parameter can be a pointer to a PARAFORMAT2 structure, which is an extension of the PARAFORMAT structure. Before sending the EM_SETPARAFORMAT message, set the structure's cbSize member to indicate the version of the structure.
Returns a nonzero value if successful, or zero otherwise.
  Windows NT: Requires version 3.51 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Unsupported.
  Header: Declared in richedit.h.
Rich Edit Controls Overview, Rich Edit Messages, PARAFORMAT, PARAFORMAT2