Different wallpaper designs dictate different ways of hanging so the design matches up.

Here's an explanation in French of "raccord sauté":
"Le papier peint à raccord sauté

Il désigne les papier dont les motifs sont décalés sur deux lés contigus. La chute de papier est plus importante. En contrepartie, on trouve souvent plus de créativité dans ces décors.
A savoir : dans les papiers à raccord (droit ou sauté), la hauteur du raccord est indiquée sur les rouleaux. Utile pour tenir compte des chutes dans le calcul du nombre de rouleaux nécessaires."
http://www.leroymerlin.fr/mpng2-front/pre?zone=zonecatalogue...

Raccord sauté = "drop match", & "raccord sauté 1/2" = (I assume) "half-drop match":

3. Drop Match

This match has several different types:

1. Half-Drop Match - Every other strip is the same at the ceiling line and the design elements run diagonally. It takes three strips to repeat the vertical design. If you numbered the strips consecutively, the odd numbered strips (1, 3, 5 and so on) would be identical and the even numbered strips (2, 4, 6, and so on) would match one another. (Note that a drop match is simply a straight match split in half.) Be sure to lightly number (in pencil) on the back of each strip the order in which they are to be hung to avoid confusion.
2. Multiple drop Match - a match that takes four or more strips before the vertical design is repeated. Similar to drop match except it takes more strips to repeat the first strip.

(http://www.doityourself.com/stry/patternmatches)