The principle of cross-community support was established as part of the Good Friday Agreement as a method to ensure that major decisions taken by the Assembly would be supported by both unionists and nationalists.
This procedure prevents contentious legislation being passed without a specified minimum degree of support from both sides of the community.
Decisions on certain matters, such as the executive's spending plans or the appointment of the presiding officer, cannot be taken without cross-community support.
Petition of concern
can bring about a cross-community vote on any issue before the Assembly, by submitting a petition of concern supported by at least 30 of the 108 MLAs to the Business Committee at least one hour before the debate is due to take place.
Such a petition delays the vote by one day.
'Weighted majority' or 'parallel consent formula'
Upon joining the Northern Ireland Assembly, MLAs designate themselves as "nationalist", "unionist" or "other".
A motion can be said to have garnered cross-community support when one of two conditions has been met.
It may either be passed by weighted majority, when at least 60% of all MLAs who vote support the motion, including at least 40% designated unionist and 40% designated nationalist.
Or it may pass in accordance with the parallel consent formula, when at least 50% of members who vote support the motion, including at least 50% unionist and 50% nationalist.