In D it usually means "no undefined behavior". For example, you can use the @safe annotation on functions. http://dlang.org/function.html#function-safety http:

In D it usually means "no undefined behavior". For example, you can use the @safe annotation on functions. http://dlang.org/function.html#function-safety http://dlang.org/function.html#function-safety http://dlang.org/safed.html http://dlang.org/safed.html