diff --git a/src/header/_aio/mod.rs b/src/header/_aio/mod.rs
index 9e32636f74..672f4e173b 100644
--- a/src/header/_aio/mod.rs
+++ b/src/header/_aio/mod.rs
@@ -1,8 +1,13 @@
+//! `aio.h` implementation.
+//!
+//! See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/aio.h.html>.
+
 use crate::{
     header::{bits_time::timespec, signal::sigevent},
     platform::types::{c_int, c_void},
 };
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/aio.h.html>.
 pub struct aiocb {
     pub aio_fildes: c_int,
     pub aio_lio_opcode: c_int,
@@ -12,16 +17,19 @@ pub struct aiocb {
     pub aio_sigevent: sigevent,
 }
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/aio_read.html>.
 // #[unsafe(no_mangle)]
 pub extern "C" fn aio_read(aiocbp: *mut aiocb) -> c_int {
     unimplemented!();
 }
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/aio_write.html>.
 // #[unsafe(no_mangle)]
 pub extern "C" fn aio_write(aiocbp: *mut aiocb) -> c_int {
     unimplemented!();
 }
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/lio_listio.html>.
 // #[unsafe(no_mangle)]
 pub extern "C" fn lio_listio(
     mode: c_int,
@@ -32,21 +40,25 @@ pub extern "C" fn lio_listio(
     unimplemented!();
 }
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/aio_error.html>.
 // #[unsafe(no_mangle)]
 pub extern "C" fn aio_error(aiocbp: *const aiocb) -> c_int {
     unimplemented!();
 }
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/aio_return.html>.
 // #[unsafe(no_mangle)]
 pub extern "C" fn aio_return(aiocbp: *mut aiocb) -> usize {
     unimplemented!();
 }
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/aio_cancel.html>.
 // #[unsafe(no_mangle)]
 pub extern "C" fn aio_cancel(fildes: c_int, aiocbp: *mut aiocb) -> c_int {
     unimplemented!();
 }
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/aio_suspend.html>.
 // #[unsafe(no_mangle)]
 pub extern "C" fn aio_suspend(
     list: *const *const aiocb,
@@ -56,6 +68,7 @@ pub extern "C" fn aio_suspend(
     unimplemented!();
 }
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/aio_fsync.html>.
 // #[unsafe(no_mangle)]
 pub extern "C" fn aio_fsync(operation: c_int, aiocbp: *mut aiocb) -> c_int {
     unimplemented!();