Within the Pavilion of the United Nations, the set of 16 stamps issued for the Expo 58 was available for sale (no other stamps were available). The postal office was also present to cancel any letter or package to be posted with the unique cancellation used from 17 April till 19 October 1958.

There were 4 postmarks available of which three at the UN Pavilion and 1 at the stamp collectors office in Brussels postal HQ. The three postmarks at the Pavilion were not identical as well as the 4th one at the Brussels postal office:

• The letter I of Verenigde Naties was placed underneath the letter R of Brussel (type 1)
• The 3rd letter E of Verenigde was placed underneath the 2nd letter S of Brussel (type 2)
• The letter G of Verenigde was placed underneath the letter U of Brussel (type 3)
• The 2nd letter E of Verenigde was placed underneath the letter B of Brussel (type 4)

It is not the aim to get all types of different UN cancellations, since this will be leading us much too far.

What is interesting though, is that the set of First Day Covers of Campo Rodan used to be cancelled on 17 April, is a second print of these covers.

They are distinctive in three easy ways:

• The colors used are brighter, especially the blue color is even darker
• The covers 61, 61a, 61b, 61d have at the right a vertical blue line
• At the back, the indication "Edition Rodan - Bruxelles, is in the outside direction

I have only found one single exception of the rule above: 1 cover 61d with the First Day Cancellation on a second print:

Many different First Day Covers with the date of 17 April are available. Among them, the most known cachet (exists in small and big format):

A less common cachet with horizontal the date 17 april 1958:

Other set of covers:

Four covers with only the stamp values which were sold separately, values 1F, 1.50F, 2.50F and 5F.

Special cover with the second cancellation issued on the last day of the Expo 58.