/usr/include/regina-normal/manifold/ is in regina-normal-dev 5.1-2build1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/regina-normal/manifold/graphloop.h
/usr/include/regina-normal/manifold/graphpair.h
/usr/include/regina-normal/manifold/graphtriple.h
/usr/include/regina-normal/manifold/handlebody.h
/usr/include/regina-normal/manifold/lensspace.h
/usr/include/regina-normal/manifold/manifold.h
/usr/include/regina-normal/manifold/ngraphloop.h
/usr/include/regina-normal/manifold/ngraphpair.h
/usr/include/regina-normal/manifold/ngraphtriple.h
/usr/include/regina-normal/manifold/nhandlebody.h
/usr/include/regina-normal/manifold/nlensspace.h
/usr/include/regina-normal/manifold/nmanifold.h
/usr/include/regina-normal/manifold/notation.h
/usr/include/regina-normal/manifold/nsfs.h
/usr/include/regina-normal/manifold/nsfsaltset.h
/usr/include/regina-normal/manifold/nsimplesurfacebundle.h
/usr/include/regina-normal/manifold/nsnappeacensusmfd.h
/usr/include/regina-normal/manifold/ntorusbundle.h
/usr/include/regina-normal/manifold/sfs.h
/usr/include/regina-normal/manifold/sfsaltset.h
/usr/include/regina-normal/manifold/simplesurfacebundle.h
/usr/include/regina-normal/manifold/snappeacensusmfd.h
/usr/include/regina-normal/manifold/torusbundle.h