Countries have to choose a specific form with which to express their contribution in the context of adopting the new climate agreement under the UNFCCC in 2015. The form and the way it is communicated and visualized, is distinct from the scale of the mitigation effort. Both the scale of the emission reductions and the form of the contribution need to respond to the strategy of a country to domestically transition to a low carbon society. Three features could be used to assess the form of contribution selected by parties: science based requirements, national policy development needs, and data and information requirements. The nature of each form of contribution has implications on how it will contribute to require by science, on how it will be implemented nationally. Data requirements are similar among the different forms, therefore it does not greatly influence the choice of form. Differences regarding the science based requirements can be overcome. This is mainly done by identifying the peaking year, being more explicit on the path towards the goal or annexing a longer term perspective. The paper conclude that the main factor to inform the choice of the form is the policy development needs. Whereas it might not always find a rational basis, perception and traditional negotiating positions play an important role in the choice of form of contribution.