It has to do with states duties to each other and the duties the federal government has to the states.
The fourth article states the duties of the states to each other and the Federal government.
The fourth article is the relationship of states to each other!
There is no Article 18 of the US Constitution.
article V of the constitution
Article V. In other words, Article 5.
Article V of the Constitution states that amendments may not, "in any Manner affect the first and fourth Clauses in the Ninth Section of the first Article; and that no State, without its Consent, shall be deprived of its equal Suffrage in the Senate." http://www.archives.gov/exhibits/charters/constitution_transcript.html
no Amendment which may be made prior to the Year One thousand eight hundred and eight shall in any Manner affect the first and fourth Clauses in the Ninth Section of the first Article; and that no State, without its Consent, shall be deprived of its equal Suffrage in the Senate. This is basically saying that no amendments can be made before 1888 and that any amendments made after that time cannot affect the first and fourth clauses of the ninth section in the first article of the constitution.
Article II of the Constitution.
Article Five
Article 3 of the constitution
The concept of Separation of Powers is embodied in the Constitution in the 1st Article, in the 2nd Article, and in the 3rd Article.
there is no such article .article number 400 and 410 are not enlisted in the constitution of india