Nope, it is just appended to the end of the string. Caveat is that ```sizeof(struct resource_acl)``` does not account at all for this, it's your responsibility to ```malloc()``` the amount you need. But it's a very nice way to stuff data into the same cacheline, very commonly used for strings (see may struct string). These are called flexible array members, and this syntax is valid in C99 (for C89 you usually do array[1]).