1) The person who has made the major contribution to the paper and/or taken the lead in writing is entitled to be the first author

2) Decisions about who should be an author, the order of authors and those included in the acknowledgements should usually be made by the first author in consultation with other authors.

3) Those who have made a major contribution to analysis or writing (i.e. more than commenting in detail on successive drafts) are entitled to follow the first author immediately; where there is a clear difference in the size of these contributions, this should be reflected in the order of these authors.

4) All others who fulfil the criteria for authorship should complete the list in alphabetical order of their surnames.

5) A maximum of five authors can be added to the paper.