 Once the autonomous communities were created, Article 145 prohibits the "federation of autonomous communities".This was understood as any agreement between communities that would produce an alteration to the political and territorial equilibrium that would cause a confrontation between different blocks of communities, an action incompatible with the principle of solidarity and the unity of the nation.The so-called "additional" and "transitory" dispositions of the constitution allowed for some exceptions to the above-mentioned framework.