Reads the DXF R12 format data of this object. 

Returns the filer status. 

This function is called by dxfIn() to allow the object to read its data. 

When overriding this function: 

1) Call assertWriteEnabled(). 2) Call the parent class's dxfInFields_R12(pFiler). 3) If it returns eOK, continue; otherwise return whatever the parent's dxfOutFields_R12(pFiler) returned. 4) Call the OdDbDxfFiler(pFiler) methods to read each of the object's data items in the order they were written. 5) Return pFiler->filerStatus().