There are quite a few certifications that you might want to familiarize yourself with as unless certified to one of the below standards or to an international equivalent (ASTM D 6400), a product and packaging item cannot be assumed to be compostable:
EN 13432:2000 for packaging. This is the European standard which certifies that packaging will compost through industrial, commercial composting within 12 weeks. Products certified as such will have under gone testing and met evaluation criteria. This standard comes under the European Directive on Packaging and Packaging Waste (94/62/EC) and has been translated and implemented in all the European Member States.
EN 14995:2006 for plastics used in wider applications than packaging. This standard is similar to EN13432 above but includes plastics used in non-packaging applications.
PAS 100: The Publicly Available Specification 100 (BSI PAS 100) is a specification that denotes a quality standard for compost. So in an ideal world our EN 13432 certified packaging will become part of PAS 100 compost.