Building numerous of pages I ran into this issue already ages ago. Because of that I had registered the issue on msconnect asking Microsoft to fix this.
Already on August 26, 2011 (!) Microsoft - by means of Stuart Glasson - answered that it had been fixed in NAV 7.
But NAV 2013 was released, and we know NAV 2013 R2 en NAV 2015 also were, but still the issue is there. o I have created a new entry for it and go there and give your vote.