def __init__(self, point_format_id, extra_dims=None):
self.id = point_format_id<EOL>if extra_dims is None:<EOL><INDENT>extra_dims = []<EOL><DEDENT>self.extra_dims = extra_dims<EOL>
Parameters
----------
point_format_id: int
    point format id
extra_dims: list of tuple
    [(name, type_str), ..] of extra dimensions attached to this point format