Good environmental status
"Good environmental status" is defined in Art. 3(5) MSFD as the environmental status of marine waters where these provide ecologically diverse and dynamic oceans and seas which are clean, healthy and productive within their intrinsic conditions, and the use of the marine environment is at a level that is sustainable, thus safeguarding the potential for uses and activities by current and future generations, i.e.:

(a) the structure, functions and processes of the constituent marine ecosystems, together with the associated physiographic, geographic, geological and climatic factors, allow those ecosystems to function fully and to maintain their resilience to human-induced environmental change. Marine species and habitats are protected, human-induced decline of biodiversity is prevented and diverse biological components function in balance;

(b) hydro-morphological, physical and chemical properties of the ecosystems, including those properties which result from human activities in the area concerned, support the ecosystems as described above. Anthropogenic inputs of substances and energy, including noise, into the marine environment do not cause pollution effects; Good environmental status shall be determined at the level of the marine region or subregion as referred to in Article 4, on the basis of the qualitative descriptors in Annex I. Adaptive management on the basis of the ecosystem approach shall be applied with the aim of attaining good environmental status.

The term "characteristic" appears in the MSFD in particular in relation to Art. 8 MSFD (in conjunction with Annex III) and Art. 9(1) MSFD (in conjunction with Annex I).

Criteria and methodological standards
Art. 9(3) MSFD vests the EU Commission with delegated powers to lay down criteria and methodological standards to be used by EU Member States when determining good environmental status. Art. 3(6) MSFD defines "criteria" as distinctive technical features that are closely linked to qualitative descriptors.

For legal MSFD purposes, the term "indicator" refers only to environmental targets (Art. 10 MSFD), where they are used to monitor progress and guide management decisions with a view to achieving these targets (Annex IV (7) MSFD). For the purposes of assessing environmental state in relation to GES, the EU Commission Decision 2010/477/EU on criteria and methodological standards refers to "indicators" to further specify the criteria and support their assessment.

GES boundary
"GES boundary" is used in the context of determining GES and status classification in order to describe in a quantified / quantifiable way whether the characteristic is in good status or not. Technically a GES boundary can be expressed in different ways, e.g. as a target value (i.e. the value must be reached or exceeded), a limit value (i.e. the state must remain below the value) or a range. Where this is not feasible for various reasons, the precautionary principle applies (see §§ 103 et seq. of the draft revised Common Understanding on how to deal with cases of uncertainty).

Environmental targets
Art. 3(7) MSFD defines "environmental target" as a qualitative or quantitative statement on the desired condition of the different components of, and pressures and impacts on, marine waters in respect of each marine region or sub-region. Environmental targets are established in accordance with Article 10.

Reference points
Among the indicative list of characteristics to be taken into account for setting environmental targets, Annex IV (8) to MSFD refers to, where appropriate, specification of reference points (target and limit reference points).

Specification and standardised methods
Art. 11(4) MSFD vests the EU Commission with delegated powers to adopt specifications and standardised methods for monitoring and assessment.