Correct assetic 'filter' syntax?

Question

Where is the correct place to put the 'filter=...' parameter?

I've seen it before / after / in between the files referenced, but I am not sure if the location makes any difference.

Moreover, is it possible to apply different filters to different files within one {% stylesheets ... %} section? For example.. to have 'xxx' apply to both files, 'yyy' apply to only to a.css & 'zzz' apply to only to b.css

{% stylesheets filter='xxx'
    'path/to/a.css' filter='yyy'
    'path/to/b.css' filter='zzz' %}<link rel="stylesheet"
type="text/css" href="{{ asset_url }}" />
{% endstylesheets %}

Answer 1

As stated in the docs, is should be after file list: http://symfony.com/doc/current/cookbook/assetic/asset_management.html#filters , but it has no importance.

To my mind you can't apply different filters to different files in the same tag.