List of bits that are set to 1 in @var{len} bytes. The bytes are
taken in big-endian order, and the bits are numbered starting with
@code{8 * @var{len} @minus{} 1} and ending with zero. For example:
-@code{bits 2} unpacks @code{#x28} @code{#x1c} to @code{(2 3 4 11 13)}
-and @code{#x1c} @code{#x28} to @code{(3 5 10 11 12)}.
+@code{bits 2} unpacks @code{#x28} @code{#x1c} to @w{@code{(2 3 4 11 13)}}
+and @code{#x1c} @code{#x28} to @w{@code{(3 5 10 11 12)}}.
@item fill @var{len}
@var{len} bytes used as a mere filler. In packing, these bytes are