Article 19 outlines various duties of the Competent Authorities under the Agreement.  Paragraph (a) authorizes and requires the Competent Authorities to conclude an Administrative Arrangement and take all necessary administrative measures to implement the Agreement as well as to designate liaison agencies.  Paragraph (b) requires the Competent Authorities to establish jointly procedures for mutual administrative assistance in administering the Agreement.  Paragraph (c) requires the Competent Authorities to notify each other of the measures they have taken unilaterally to implement the Agreement and paragraph (d) obligates the Competent Authorities to notify each other of any changes in their respective social security laws that may affect the application of the Agreement.