- [proc_macro](language-features/proc-macro.md)
- [quote](language-features/quote.md)
- [relaxed_adts](language-features/relaxed-adts.md)
+ - [repr_align](language-features/repr-align.md)
- [repr_simd](language-features/repr-simd.md)
- [rustc_attrs](language-features/rustc-attrs.md)
- [rustc_diagnostic_macros](language-features/rustc-diagnostic-macros.md)
- [alloc_system](library-features/alloc-system.md)
- [alloc](library-features/alloc.md)
- [as_c_str](library-features/as-c-str.md)
- - [as_unsafe_cell](library-features/as-unsafe-cell.md)
- [ascii_ctype](library-features/ascii-ctype.md)
- - [binary_heap_extras](library-features/binary-heap-extras.md)
- [binary_heap_peek_mut_pop](library-features/binary-heap-peek-mut-pop.md)
- - [borrow_state](library-features/borrow-state.md)
- [box_heap](library-features/box-heap.md)
- [c_void_variant](library-features/c-void-variant.md)
- [char_escape_debug](library-features/char-escape-debug.md)
- [derive_clone_copy](library-features/derive-clone-copy.md)
- [derive_eq](library-features/derive-eq.md)
- [discriminant_value](library-features/discriminant-value.md)
- - [enumset](library-features/enumset.md)
- [error_type_id](library-features/error-type-id.md)
- [exact_size_is_empty](library-features/exact-size-is-empty.md)
- [fd](library-features/fd.md)
- [fd_read](library-features/fd-read.md)
- [fixed_size_array](library-features/fixed-size-array.md)
- [float_bits_conv](library-features/float-bits-conv.md)
- - [float_extras](library-features/float-extras.md)
- [flt2dec](library-features/flt2dec.md)
- [fmt_flags_align](library-features/fmt-flags-align.md)
- [fmt_internals](library-features/fmt-internals.md)
- [io_error_internals](library-features/io-error-internals.md)
- [io](library-features/io.md)
- [ip](library-features/ip.md)
- - [is_unique](library-features/is-unique.md)
- [iter_rfind](library-features/iter-rfind.md)
- [libstd_io_internals](library-features/libstd-io-internals.md)
- [libstd_sys_internals](library-features/libstd-sys-internals.md)
- [linked_list_extras](library-features/linked-list-extras.md)
- [lookup_host](library-features/lookup-host.md)
- [manually_drop](library-features/manually-drop.md)
- - [map_entry_recover_keys](library-features/map-entry-recover-keys.md)
+ - [more_io_inner_methods](library-features/more-io-inner-methods.md)
- [mpsc_select](library-features/mpsc-select.md)
- [n16](library-features/n16.md)
- [never_type_impls](library-features/never-type-impls.md)
- [rand](library-features/rand.md)
- [range_contains](library-features/range-contains.md)
- [raw](library-features/raw.md)
- - [rc_would_unwrap](library-features/rc-would-unwrap.md)
- [retain_hash_collection](library-features/retain-hash-collection.md)
- [reverse_cmp_key](library-features/reverse-cmp-key.md)
- [rt](library-features/rt.md)
- [slice_rsplit](library-features/slice-rsplit.md)
- [sort_internals](library-features/sort-internals.md)
- [sort_unstable](library-features/sort-unstable.md)
+ - [splice](library-features/splice.md)
- [step_by](library-features/step-by.md)
- [step_trait](library-features/step-trait.md)
- [str_checked_slicing](library-features/str-checked-slicing.md)
- [str_escape](library-features/str-escape.md)
- [str_internals](library-features/str-internals.md)
+ - [str_box_extras](library-features/str-box-extras.md)
- [str_mut_extras](library-features/str-mut-extras.md)
- [test](library-features/test.md)
- [thread_id](library-features/thread-id.md)
- [windows_handle](library-features/windows-handle.md)
- [windows_net](library-features/windows-net.md)
- [windows_stdio](library-features/windows-stdio.md)
- - [zero_one](library-features/zero-one.md)
->>>>>> Add top level sections to the Unstable Book.