diff --git a/src/header/netinet_in/mod.rs b/src/header/netinet_in/mod.rs
index 4621b85b33214710ee8e4c4b3900b11825720d55..cec0498c4d7791a737389c9790f3a9c9ed4873be 100644
--- a/src/header/netinet_in/mod.rs
+++ b/src/header/netinet_in/mod.rs
@@ -1,3 +1,7 @@
+//! `netinet/in.h` implementation.
+//!
+//! See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
+
 #![allow(non_camel_case_types)]
 
 use crate::{
@@ -5,20 +9,25 @@ use crate::{
     platform::types::*,
 };
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 pub type in_addr_t = u32;
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 pub type in_port_t = u16;
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 #[repr(C)]
 #[derive(Debug, Clone, Copy, Default)]
 pub struct in_addr {
     pub s_addr: in_addr_t,
 }
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 #[repr(C)]
 pub struct in6_addr {
     pub s6_addr: [u8; 16],
 }
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 #[repr(C)]
 #[derive(Debug, Default)]
 pub struct sockaddr_in {
@@ -28,6 +37,7 @@ pub struct sockaddr_in {
     pub sin_zero: [c_char; 8],
 }
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 #[repr(C)]
 pub struct sockaddr_in6 {
     pub sin6_family: sa_family_t,
@@ -37,6 +47,7 @@ pub struct sockaddr_in6 {
     pub sin6_scope_id: u32,
 }
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 #[repr(C)]
 pub struct ipv6_mreq {
     pub ipv6mr_multiaddr: in6_addr,
@@ -44,49 +55,84 @@ pub struct ipv6_mreq {
 }
 
 // Address String Lengths
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 pub const INET_ADDRSTRLEN: c_int = 16;
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 pub const INET6_ADDRSTRLEN: c_int = 46;
 
 // IP options
+/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man7/ip.7.html>.
 pub const IP_TOS: c_int = 1;
+/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man7/ip.7.html>.
 pub const IP_RECVTOS: c_int = 13;
 
 // Protocol Numbers
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 pub const IPPROTO_IP: u8 = 0;
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 pub const IPPROTO_ICMP: u8 = 1;
+/// Non-POSIX.
 pub const IPPROTO_IGMP: u8 = 2;
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 pub const IPPROTO_TCP: u8 = 6;
+/// Non-POSIX.
 pub const IPPROTO_PUP: u8 = 12;
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 pub const IPPROTO_UDP: u8 = 17;
+/// Non-POSIX.
 pub const IPPROTO_IDP: u8 = 22;
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 pub const IPPROTO_IPV6: u8 = 41;
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 pub const IPPROTO_RAW: u8 = 0xff;
+/// Non-POSIX.
 pub const IPPROTO_MAX: u8 = 0xff;
 
+/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man7/ip.7.html>.
 pub const IP_TTL: c_int = 2;
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 pub const IPV6_UNICAST_HOPS: c_int = 16;
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 pub const IPV6_MULTICAST_IF: c_int = 17;
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 pub const IPV6_MULTICAST_HOPS: c_int = 18;
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 pub const IPV6_MULTICAST_LOOP: c_int = 19;
+/// Non-POSIX.
 pub const IPV6_ADD_MEMBERSHIP: c_int = 20;
+/// Non-POSIX.
 pub const IPV6_DROP_MEMBERSHIP: c_int = 21;
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 pub const IPV6_V6ONLY: c_int = 26;
+/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man7/ip.7.html>.
 pub const IP_MULTICAST_IF: c_int = 32;
+/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man7/ip.7.html>.
 pub const IP_MULTICAST_TTL: c_int = 33;
+/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man7/ip.7.html>.
 pub const IP_MULTICAST_LOOP: c_int = 34;
+/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man7/ip.7.html>.
 pub const IP_ADD_MEMBERSHIP: c_int = 35;
+/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man7/ip.7.html>.
 pub const IP_DROP_MEMBERSHIP: c_int = 36;
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 pub const INADDR_ANY: u32 = 0; // Can't use in_addr_t alias because cbindgen :(
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 pub const INADDR_BROADCAST: u32 = 0xFFFF_FFFF; // Can't use core::u32::MAX because cbindgen :(
+/// Non-POSIX.
 pub const INADDR_NONE: u32 = 0xFFFF_FFFF;
+/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man7/ip.7.html>.
 pub const INADDR_LOOPBACK: u32 = 0x7F00_0001;
-
+/// Non-POSIX.
 pub const INADDR_UNSPEC_GROUP: u32 = 0xE000_0000;
+/// Non-POSIX.
 pub const INADDR_ALLHOSTS_GROUP: u32 = 0xE000_0001;
+/// Non-POSIX.
 pub const INADDR_ALLRTRS_GROUP: u32 = 0xE000_0002;
+/// Non-POSIX.
 pub const INADDR_MAX_LOCAL_GROUP: u32 = 0xE000_00FF;
 
+/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man7/ip.7.html>.
 #[repr(C)]
 pub struct ip_mreq_source {
     pub imr_multiaddr: in_addr,
@@ -94,18 +140,21 @@ pub struct ip_mreq_source {
     pub imr_sourceaddr: in_addr,
 }
 
+/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man7/ip.7.html>.
 #[repr(C)]
 pub struct ip_mreq {
     pub imr_multiaddr: in_addr,
     pub imr_interface: in_addr,
 }
 
+/// Non-POSIX.
 #[repr(C)]
 pub struct group_req {
     pub gr_interface: u32,
     pub gr_group: sockaddr_storage,
 }
 
+/// Non-POSIX.
 #[repr(C)]
 pub struct group_source_req {
     pub gsr_interface: u32,
@@ -113,11 +162,13 @@ pub struct group_source_req {
     pub gsr_source: sockaddr_storage,
 }
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 #[no_mangle]
 pub static in6addr_any: in6_addr = in6_addr {
     s6_addr: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
 };
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html>.
 #[no_mangle]
 pub static in6addr_loopback: in6_addr = in6_addr {
     s6_addr: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
diff --git a/src/header/netinet_ip/mod.rs b/src/header/netinet_ip/mod.rs
index 8b137891791fe96927ad78e64b0aad7bded08bdc..30ddb6ebf4c272b5b05906daebfaf0f91401f759 100644
--- a/src/header/netinet_ip/mod.rs
+++ b/src/header/netinet_ip/mod.rs
@@ -1 +1,3 @@
-
+//! `netinet/ip.h` implementation.
+//!
+//! Non-POSIX.
diff --git a/src/header/netinet_tcp/mod.rs b/src/header/netinet_tcp/mod.rs
index deaf15f95e650f68e443ecf83e24ba015989b48d..bd8a902035c0d83a5f9e5dca202c2ab124693fa0 100644
--- a/src/header/netinet_tcp/mod.rs
+++ b/src/header/netinet_tcp/mod.rs
@@ -1,7 +1,16 @@
+//! `netinet/tcp.h` implementation.
+//!
+//! See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_tcp.h.html>.
+
 use crate::platform::types::*;
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_tcp.h.html>.
 pub const TCP_NODELAY: c_int = 1;
+/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man7/tcp.7.html>.
 pub const TCP_MAXSEG: c_int = 2;
+/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man7/tcp.7.html>.
 pub const TCP_KEEPIDLE: c_int = 4;
+/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man7/tcp.7.html>.
 pub const TCP_KEEPINTVL: c_int = 5;
+/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man7/tcp.7.html>.
 pub const TCP_KEEPCNT: c_int = 6;