def create_geodict_structure(gd=None):
    """
    Creates the geojson dictionnary structure.

    :param gd: an empty OrderedDict
    :return: None
    """
    if gd is not None:
        gd['type'] = 'FeatureCollection'
        gd['crs'] = {'type': 'name', 'properties': {'name':
            'urn:ogc:def:crs:OSG:2:84'}}
        gd['features'] = []
