/usr/include/linbox/field/Modular/ is in liblinbox-dev 1.3.2-1.1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/linbox/field/Modular/modular-balanced-double.h
/usr/include/linbox/field/Modular/modular-balanced-float.h
/usr/include/linbox/field/Modular/modular-balanced-int32.h
/usr/include/linbox/field/Modular/modular-balanced-int64.h
/usr/include/linbox/field/Modular/modular-byte.h
/usr/include/linbox/field/Modular/modular-crooked-double.h
/usr/include/linbox/field/Modular/modular-double.h
/usr/include/linbox/field/Modular/modular-float.h
/usr/include/linbox/field/Modular/modular-int32.h
/usr/include/linbox/field/Modular/modular-int64.h
/usr/include/linbox/field/Modular/modular-short.h
/usr/include/linbox/field/Modular/modular-unsigned.h
/usr/include/linbox/field/Modular/modular.inl