13 Further to the criteria set out in the treaties, other factors may affect the candidature of specific individuals. For example, the appointment of individual experts to special procedure mandates of the Human Rights Council is subject to the principle of non-accumulation of concurrent human rights functions.8 While the treaties do not refer to this principle, the implication is that special procedure mandate holders who wish to seek nomination as treaty body members should first resign their mandates. When electing members, States parties should also give due consideration to a range of factors such as equitable geographical distribution, and the representation of the different forms of civilization and of the principal legal systems.9 Only the Committee on Economic, Social and Cultural Rights is formally subject to membership allocation on a regional basis. Fifteen of its eighteen seats must be equally distributed among the five regional groups (as recognized by the United Nations); the other three are allocated in accordance with the increase in the total number of States parties per regional group. Recent treaties, as well as General Assembly resolution 68/268, also require States parties to consider gender balance and the participation of experts with disabilities. Table 4 sets out the gender balance of each treaty body on 1 August 2015. In addition to the qualifications and requirements set out in the treaties and in General Assembly resolutions, individuals interested in being nominated for election as treaty body members should consider their availability to prepare for and attend all treaty body meetings as well as their ability to work confidently in at least one of the working languages of the treaty body. It should be noted that the General Assembly, in its resolution 68/268 (para. 30), limits the working languages of the committees to three, generally English, French and Spanish. 8 9 Human Rights Council resolution 5/1, para. 44. General Assembly resolution 68/268, para. 13.