The IDL fragments in the filter effects spec:
http://www.w3.org/TR/filter-effects/
...are missing indentation: interface members are not indented, but should have 2 spaces of indentation, for consistency.

I.e., it's written as:
interface Foo {
attribute SVGType a;
attribute SVGType b;
};
...instead of:
interface Foo {
  attribute SVGType a;
  attribute SVGType b;
};
...instead of:

In the Web IDL spec and SVG 2 spec, these are given with 2 spaces of indentation.
This is a minor point (style-only), but it's pretty glaring.

Refs:
http://heycam.github.io/webidl/
http://www.w3.org/TR/SVG2/