[2] [CITE@en[RFC 793 - Transmission Control Protocol]] ([TIME[2014-12-29 14:15:21 +09:00]] 版) <https://tools.ietf.org/html/rfc793>

[1] [CITE@en[RFC 6093 - On the Implementation of the TCP Urgent Mechanism]] ([TIME[2015-02-15 16:16:20 +09:00]] 版) <https://tools.ietf.org/html/rfc6093>

[3] [CITE@ja-jp[URGパケット ‐ 通信用語の基礎知識]]
([TIME[2015-03-07 15:47:05 +09:00]] 版)
<http://www.wdic.org/w/WDIC/URG%E3%83%91%E3%82%B1%E3%83%83%E3%83%88>

[4] [CITE@ja-jp[out of band攻撃 ‐ 通信用語の基礎知識]]
([TIME[2015-03-07 15:47:23 +09:00]] 版)
<http://www.wdic.org/w/WDIC/out%20of%20band%E6%94%BB%E6%92%83>

[5] [CITE[Man page of TCP]]
([TIME[2015-02-06 06:34:08 +09:00]] 版)
<http://linuxjm.sourceforge.jp/html/LDP_man-pages/man7/tcp.7.html>

[6] [CITE[The GNU C Library: Out-of-Band Data]]
([TIME[2015-06-15 12:17:45 +09:00]] 版)
<http://www.gnu.org/software/libc/manual/html_node/Out_002dof_002dBand-Data.html>

[FIG(quote)[
[FIGCAPTION[
[7] [CITE@en[RFC 793 - Transmission Control Protocol]]
([TIME[2015-07-11 23:50:25 +09:00]] 版)
<https://tools.ietf.org/html/rfc793>
]FIGCAPTION]

> 
>   Urgent Pointer:  16 bits
>     This field communicates the current value of the urgent pointer as a
>     positive offset from the sequence number in this segment.  The
>     urgent pointer points to the sequence number of the octet following
>     the urgent data.  This field is only be interpreted in segments with
>     the URG control bit set.

]FIG]