fee and the method of its payment, due regard must be paid to the supply of and demand for the frequencies being put to tender, the level of development of the market to which the frequencies being put to tender relate, and the level of such fees in other Member States. It may in no case be so high as to hinder the development of innovative services and competition in the market. Article 61 (supervision and construction of a monitoring and measuring system) (1) The Agency shall oversee implementation of the provisions of this Chapter and the implementation of the decisions issued pursuant thereto. (2) The Agency shall, for the purposes of managing and monitoring the radio frequency spectrum, establish and construct a national control and measurement system. (3) The construction referred to in the preceding paragraph shall be for the public benefit. VI. NUMBERING Article 62 (objectives and management) (1) The Agency shall, pursuant to public authorisation, manage the set of all numbering resources used in the Republic of Slovenia with the objective of ensuring their efficient structuring and use and the objective of satisfying the needs of undertakings and other natural persons and legal entities eligible to acquire a decision allocating numbering resources in a fair and non-discriminatory manner under this Act. In doing so, the Agency shall take into account any strategic documents of the Republic of Slovenia and the EU, as well as the strategic guidelines of the ministry responsible for electronic communications. (2) The Agency shall manage all information relating to the management of numbering resources. (3) The Agency shall publish on its website information on the numbers and number blocks allocated, as follows: 1. number or number block; 2. holders of numbers or number blocks. Article 63 (numbering plan) (1) The numbering plan shall be adopted by the Agency by means of a general act. (2) The numbering plan shall lay down the type, length, structure, purpose and method of use of numbering resources, including numbers for emergency calls and numbers whose use is harmonised on the basis of EU regulations, and must also enable the portability of numbers and the introduction of new electronic communications services. (3) Changes or additions to the numbering plan that significantly affect the numbering system and whose implementation is technologically complex shall not be applied until two years after their entry into force. Article 64 (use of numbering resources) The undertakings and natural persons or legal entities referred to in the first paragraph of