What is the meaning of “Visé Paris”?

The phrase “Visé Paris” (sometimes spelled Vise Paris or Visa Paris) frequently appeared on postcards printed in France during WW1, often on the reverse. Usually - but not always - it was followed by a number, or it referred to a number on the front of the postcard, and was preceded by some information about the editor, publisher or printer.
For example: Imp. P. Gaultier, Boulogne-s-Mer. – Ed. P. G. Visé Paris 800 was printed on the reverse of Mackain's Out on Rest postcards by Gaultier:

Whereas Visé Paris 800 appears by itself on the front of the same set of Mackain cards by Savigny:

It has been suggested that “Visé” was the name of a publishing house or printer in Paris, but the weight of evidence is that it is more likely some sort of official stamp of approval by the military authorities. Vise can mean “endorsed”, “stamp” or “authorization” depending on the context (as in a travel visa) and Gaultier was a printer based in Boulogne while Savigny was in Paris.The numbering following “Visé Paris” appears to be chronological - Mackain's card sets are numbered 713, 763, and 800, and were “authorized” late in 1917.

Set	Reverse	Front
		Gaultier	Savigny (Long)	Savigny (Short)
Greetings Cards	Imp. G. Savigny, Paris. – P.G. – Visa Paris 713		-
	Paris. – Imp. G. Savigny, 80, rue de Cléry.			Visé Paris 713
In Training	Imp. P. Gaultier, Boulogne-s-Mer. – Ed. P. G. Visé 9-10-17	-
	Imp. G. Savigny, Paris – P.G.		-
	Paris. – Imp. G. Savigny, 80, rue de Cléry.			-
At the Base	Imp. P. Gaultier, Boulogne-s-Mer. – Ed. P. G. Visé 1-11-17	-
	Imp. G. Savigny, Paris – P.G.		-
	Paris. – Imp. G. Savigny, 80, rue de Cléry.			-
Up the Line	Imp. P. Gaultier, Boulogne-s-Mer. – Ed. P. G. Visé Paris 763	-
	Imp. G. Savigny, Paris – P.G.		Visé Paris 763
	Paris. – Imp. G. Savigny, 80, rue de Cléry.			Visé Paris 763
Out on Rest	Imp. P. Gaultier, Boulogne-s-Mer. – Ed. P. G. Visé Paris 800	-
	Imp. G. Savigny, Paris – P.G.		Visé Paris 800
	Paris. – Imp. G. Savigny, 80, rue de Cléry.			Visé Paris 800
Cheerful Tommy	Imp. P. Gaultier, Boulogne-s-Mer. – Ed. P. G. Visé 18-1-18	-

Non-Mackain cards with lower numbers appeared in 1914 and the numbers rise in line with time.
Was there a central “approval process” during WW1 for cards to be reviewed by the military authorities in Paris prior to publishing? If so, did they assign a unique number to each card (or set of cards) in ascending order? And what were they reviewing for content ... military secrets? Whereabouts of troops? Seditious content? Or does “Visé Paris” mean something else entirely?
If anyone has any thoughts on this, or evidence to support it (or a better theory), please share!