Portable version of NetBSD make
Bmake is derived from NetBSD's make(1), its goal is to be a portable version of same, so new features are added via imports of NetBSD's make (I'm one of the contributors to NetBSD). Thus bmake is kept in sync with NetBSD's make.
This version of Make features several extensions that are not in GNU Make, and does not has all of GNU Make extensions. Some projects explicitly require one or the other.