Why does the B-2 Spirit have a pattern of thin white lines? Northrop Grumman's B-2 Spirit bomber is mostly black or dark grey, but has a symmetric pattern of distinctive, thin white lines painted on its wings and fuselage. I have not been able to find anything similar on other airplanes, so why does the B-2 have these lines and what is their purpose?
@RAC and @Hobbes are right. I found a high res photo on defense.gov.

The crop below shows WALKWAY and NO STEP instructions indeed. Similar to what you'd find on a jetliner's wing.



It makes me wonder though why the person below did not abide.


Source: https://tucson.com/news/national/costly-b--bombers-both-tech-marvels-hangar-queens/article_273b0f50-71f6-56ca-a399-401e342658c1.html