http://www.pfma.com/public/index.htmYou might find the info you require here.
The ingredients must be listed in descending order by weight. They can be indicated using category names, which are laid down by the Regulations, such as 'meat and animal derivatives', 'cereals', 'derivatives of vegetable origin'. Alternatively ingredients can be listed by their own individual names*. When an ingredient is used that does not fall into any of the prescribed categories, its individual name must be listed. In all other circumstances, mixing individual names and category names in the ingredients list is not permitted. If particular attention is drawn to a specific ingredient (eg With Chicken), the percentage of that ingredient component must also be listed.