<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:dt="uuid:C2F41010-65B3-11d1-A29F-00AA00C14882" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<meta name="Microsoft Theme 2.00" content="Concrete 111">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<!--[if !mso]><style>v\:* {behavior:url(#default#VML);}
o\:* {behavior:url(#default#VML);}
w\:* {behavior:url(#default#VML);}
.shape {behavior:url(#default#VML);}
</style><![endif]--><style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Verdana;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Verdana",sans-serif;
color:#176050;}
h1
{mso-style-priority:9;
mso-style-link:"Heading 1 Char";
margin-top:12.0pt;
margin-right:0in;
margin-bottom:0in;
margin-left:0in;
margin-bottom:.0001pt;
page-break-after:avoid;
font-size:16.0pt;
font-family:"Verdana",sans-serif;
color:#176050;}
h2
{mso-style-priority:9;
mso-style-link:"Heading 2 Char";
margin-top:2.0pt;
margin-right:0in;
margin-bottom:0in;
margin-left:0in;
margin-bottom:.0001pt;
page-break-after:avoid;
font-size:14.0pt;
font-family:"Verdana",sans-serif;
color:#176050;
font-weight:normal;}
h3
{mso-style-priority:9;
mso-style-link:"Heading 3 Char";
margin-top:2.0pt;
margin-right:0in;
margin-bottom:0in;
margin-left:0in;
margin-bottom:.0001pt;
page-break-after:avoid;
font-size:13.0pt;
font-family:"Verdana",sans-serif;
color:#176050;
font-weight:normal;}
h4
{mso-style-priority:9;
mso-style-link:"Heading 4 Char";
margin-top:2.0pt;
margin-right:0in;
margin-bottom:0in;
margin-left:0in;
margin-bottom:.0001pt;
page-break-after:avoid;
font-size:14.0pt;
font-family:"Verdana",sans-serif;
color:#176050;
font-weight:normal;}
h5
{mso-style-priority:9;
mso-style-link:"Heading 5 Char";
margin-top:2.0pt;
margin-right:0in;
margin-bottom:0in;
margin-left:0in;
margin-bottom:.0001pt;
page-break-after:avoid;
font-size:13.0pt;
font-family:"Verdana",sans-serif;
color:#176050;
font-weight:normal;}
h6
{mso-style-priority:9;
mso-style-link:"Heading 6 Char";
margin-top:2.0pt;
margin-right:0in;
margin-bottom:0in;
margin-left:0in;
margin-bottom:.0001pt;
page-break-after:avoid;
font-size:11.0pt;
font-family:"Verdana",sans-serif;
color:#176050;
font-weight:normal;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:#00B013;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:#00870F;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal-compose;
color:#176050;}
span.Heading1Char
{mso-style-name:"Heading 1 Char";
mso-style-priority:9;
mso-style-link:"Heading 1";
font-family:"Verdana",sans-serif;
color:#176050;
font-weight:bold;}
span.Heading2Char
{mso-style-name:"Heading 2 Char";
mso-style-priority:9;
mso-style-link:"Heading 2";
font-family:"Verdana",sans-serif;
color:#176050;}
span.Heading3Char
{mso-style-name:"Heading 3 Char";
mso-style-priority:9;
mso-style-link:"Heading 3";
font-family:"Verdana",sans-serif;
color:#176050;}
span.Heading4Char
{mso-style-name:"Heading 4 Char";
mso-style-priority:9;
mso-style-link:"Heading 4";
font-family:"Verdana",sans-serif;
color:#176050;}
span.Heading5Char
{mso-style-name:"Heading 5 Char";
mso-style-priority:9;
mso-style-link:"Heading 5";
font-family:"Verdana",sans-serif;
color:#176050;}
span.Heading6Char
{mso-style-name:"Heading 6 Char";
mso-style-priority:9;
mso-style-link:"Heading 6";
font-family:"Verdana",sans-serif;
color:#176050;}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri",sans-serif;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body bgcolor="white" background="cid:image001.gif@01D63340.C252AD10" lang="EN-US" link="#00B013" vlink="#00870F">
<img src="cid:image001.gif@01D63340.C252AD10" v:src="cid:image001.gif@01D63340.C252AD10" v:shapes="_x0000_Mail" width="0" height="0" class="shape" style="display:none;width:0;height:0"><!--[if gte mso 9]><xml>
<v:background id="_x0000_s1025" o:bwmode="white" o:targetscreensize="1024,768">
<v:fill src="cid:image001.gif@01D63340.C252AD10" o:title="background_concrete" type="frame" />
</v:background></xml><![endif]-->
<div class="WordSection1">
<p class="MsoNormal"><a name="_GoBack"></a>Jeff, Cheryl, et al – below I paste the IETF definitions that were linked – note, for example, that “should” says “can be ignored” under certain circumstances – not sure anyone in the WG ever had that understanding
of “should”.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Anne<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext">Network Working Group S. Bradner<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext">Request for Comments: 2119 Harvard University<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext">BCP: 14 March 1997<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext">Category: Best Current Practice<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext">
<b><o:p></o:p></b></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span lang="EN" style="font-family:"Courier New";color:windowtext">Key words for use in RFCs to Indicate Requirement Levels</span></b><b><span style="font-family:"Courier New";color:windowtext"><o:p></o:p></span></b></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext">Status of this Memo<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> This document specifies an Internet Best Current Practices for the<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> Internet Community, and requests discussion and suggestions for<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> improvements. Distribution of this memo is unlimited.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext">Abstract<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> In many standards track documents several words are used to signify<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> the requirements in the specification. These words are often<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> capitalized. This document defines these words as they should be<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> interpreted in IETF documents. Authors who follow these guidelines<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> should incorporate this phrase near the beginning of their document:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> "OPTIONAL" in this document are to be interpreted as described in<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext">
<a href="https://tools.ietf.org/html/rfc2119"><span style="color:blue">RFC 2119</span></a>.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> Note that the force of these words is modified by the requirement<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> level of the document in which they are used.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="section-1"></a><a href="https://tools.ietf.org/html/rfc2119#section-1"><span style="mso-bookmark:section-1"><b><span lang="EN" style="font-family:"Courier New";color:black">1</span></b></span><span style="mso-bookmark:section-1"></span></a><span style="mso-bookmark:section-1"></span><b><span lang="EN" style="font-family:"Courier New";color:windowtext">.
MUST <o:p></o:p></span></b></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> This word, or the terms "REQUIRED" or "SHALL", mean that the<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> definition is an absolute requirement of the specification.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="section-2"></a><a href="https://tools.ietf.org/html/rfc2119#section-2"><span style="mso-bookmark:section-2"><b><span lang="EN" style="font-family:"Courier New";color:black">2</span></b></span><span style="mso-bookmark:section-2"></span></a><span style="mso-bookmark:section-2"></span><b><span lang="EN" style="font-family:"Courier New";color:windowtext">.
MUST NOT <o:p></o:p></span></b></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> This phrase, or the phrase "SHALL NOT", mean that the<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> definition is an absolute prohibition of the specification.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="section-3"></a><a href="https://tools.ietf.org/html/rfc2119#section-3"><span style="mso-bookmark:section-3"><b><span lang="EN" style="font-family:"Courier New";color:black">3</span></b></span><span style="mso-bookmark:section-3"></span></a><span style="mso-bookmark:section-3"></span><b><span lang="EN" style="font-family:"Courier New";color:windowtext">.
SHOULD <o:p></o:p></span></b></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> This word, or the adjective "RECOMMENDED", mean that there<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> may exist valid reasons in particular circumstances to ignore a<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> particular item, but the full implications must be understood and<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> carefully weighed before choosing a different course.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="section-4"></a><a href="https://tools.ietf.org/html/rfc2119#section-4"><span style="mso-bookmark:section-4"><b><span lang="EN" style="font-family:"Courier New";color:black">4</span></b></span><span style="mso-bookmark:section-4"></span></a><span style="mso-bookmark:section-4"></span><b><span lang="EN" style="font-family:"Courier New";color:windowtext">.
SHOULD NOT <o:p></o:p></span></b></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> This phrase, or the phrase "NOT RECOMMENDED" mean that<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> there may exist valid reasons in particular circumstances when the<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> particular behavior is acceptable or even useful, but the full<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> implications should be understood and the case carefully weighed<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"> before implementing any behavior described with this label.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN" style="font-family:"Courier New";color:windowtext">Bradner Best Current Practice [Page 1]<o:p></o:p></span></p>
<div class="MsoNormal"><span lang="EN" style="font-family:"Times New Roman",serif;color:windowtext">
<hr size="2" width="768" style="width:8.0in" align="left">
</span></div>
<p class="MsoNormal" style="page-break-before:always"><a name="page-2"></a><a href="https://tools.ietf.org/html/rfc2119#page-2"><span style="mso-bookmark:page-2"><span lang="EN" style="font-family:"Courier New";color:white"></span></span><span style="mso-bookmark:page-2"></span></a><span style="mso-bookmark:page-2"></span><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"><a href="https://tools.ietf.org/html/rfc2119"><span style="color:blue">RFC 2119</span></a> RFC Key Words
March 1997<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;page-break-before:always">
<a name="section-5"></a><a href="https://tools.ietf.org/html/rfc2119#section-5"><span style="mso-bookmark:section-5"><b><span lang="EN" style="font-family:"Courier New";color:black">5</span></b></span><span style="mso-bookmark:section-5"></span></a><span style="mso-bookmark:section-5"></span><b><span lang="EN" style="font-family:"Courier New";color:windowtext">.
MAY <o:p></o:p></span></b></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> This word, or the adjective "OPTIONAL", mean that an item is<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> truly optional. One vendor may choose to include the item because a<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> particular marketplace requires it or because the vendor feels that<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> it enhances the product while another vendor may omit the same item.<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> An implementation which does not include a particular option MUST be<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> prepared to interoperate with another implementation which does<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> include the option, though perhaps with reduced functionality. In the<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> same vein an implementation which does include a particular option<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> MUST be prepared to interoperate with another implementation which<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> does not include the option (except, of course, for the feature the<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> option provides.)<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;page-break-before:always">
<a name="section-6"></a><a href="https://tools.ietf.org/html/rfc2119#section-6"><span style="mso-bookmark:section-6"><b><span lang="EN" style="font-family:"Courier New";color:black">6</span></b></span><span style="mso-bookmark:section-6"></span></a><span style="mso-bookmark:section-6"></span><b><span lang="EN" style="font-family:"Courier New";color:windowtext">.
Guidance in the use of these Imperatives<o:p></o:p></span></b></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> Imperatives of the type defined in this memo must be used with care<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> and sparingly. In particular, they MUST only be used where it is<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> actually required for interoperation or to limit behavior which has<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> potential for causing harm (e.g., limiting retransmisssions) For<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> example, they must not be used to try to impose a particular method<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> on implementors where the method is not required for<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> interoperability.<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;page-break-before:always">
<a name="section-7"></a><a href="https://tools.ietf.org/html/rfc2119#section-7"><span style="mso-bookmark:section-7"><b><span lang="EN" style="font-family:"Courier New";color:black">7</span></b></span><span style="mso-bookmark:section-7"></span></a><span style="mso-bookmark:section-7"></span><b><span lang="EN" style="font-family:"Courier New";color:windowtext">.
Security Considerations<o:p></o:p></span></b></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> These terms are frequently used to specify behavior with security<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> implications. The effects on security of not implementing a MUST or<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> SHOULD, or doing something the specification says MUST NOT or SHOULD<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> NOT be done may be very subtle. Document authors should take the time<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> to elaborate the security implications of not following<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> recommendations or requirements as most implementors will not have<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> had the benefit of the experience and discussion that produced the<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> specification.<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;page-break-before:always">
<a name="section-8"></a><a href="https://tools.ietf.org/html/rfc2119#section-8"><span style="mso-bookmark:section-8"><b><span lang="EN" style="font-family:"Courier New";color:black">8</span></b></span><span style="mso-bookmark:section-8"></span></a><span style="mso-bookmark:section-8"></span><b><span lang="EN" style="font-family:"Courier New";color:windowtext">.
Acknowledgments<o:p></o:p></span></b></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> The definitions of these terms are an amalgam of definitions taken<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> from a number of RFCs. In addition, suggestions have been<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> incorporated from a number of people including Robert Ullmann, Thomas<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"> Narten, Neal McBurnett, and Robert Elz.<o:p></o:p></span></p>
<p class="MsoNormal" style="page-break-before:always"><span lang="EN" style="font-family:"Courier New";color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<table class="TableGridLight1" border="0" cellspacing="0" cellpadding="0" style="border-collapse:collapse;border:none">
<tbody>
<tr>
<td width="336" valign="top" style="width:3.5in;padding:0in 5.4pt 0in 5.4pt">
<p class="MsoNormal" style="line-height:105%"><b><span style="font-size:9.0pt;line-height:105%;font-family:"Arial",sans-serif;color:#AF272F">Anne E. Aikman-Scalese</span></b><span style="font-size:11.0pt;line-height:105%;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td width="336" valign="top" style="width:3.5in;padding:0in 5.4pt 0in 5.4pt">
<p class="MsoNormal" style="line-height:105%"><span style="font-size:9.0pt;line-height:105%;font-family:"Arial",sans-serif;color:#323232">Of Counsel</span><span style="font-size:11.0pt;line-height:105%;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td width="336" valign="top" style="width:3.5in;padding:0in 5.4pt 0in 5.4pt">
<p class="MsoNormal" style="line-height:105%"><span style="font-size:9.0pt;line-height:105%;font-family:"Arial",sans-serif;color:#323232">520.629.4428 office</span><span style="font-size:11.0pt;line-height:105%;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td width="336" valign="top" style="width:3.5in;padding:0in 5.4pt 0in 5.4pt">
<p class="MsoNormal" style="line-height:105%"><span style="font-size:9.0pt;line-height:105%;font-family:"Arial",sans-serif;color:#323232">520.879.4725 fax</span><span style="font-size:11.0pt;line-height:105%;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td width="336" valign="top" style="width:3.5in;padding:0in 5.4pt 0in 5.4pt">
<p class="MsoNormal" style="line-height:105%"><span style="font-size:9.0pt;line-height:105%;font-family:"Arial",sans-serif"><a href="mailto:AAikman@lrrc.com" target="_new" title="Email User"><span style="color:#AF272F">AAikman@lrrc.com</span></a></span><span style="font-size:11.0pt;line-height:105%;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td width="336" valign="top" style="width:3.5in;padding:0in 5.4pt 0in 5.4pt">
<p class="MsoNormal" style="line-height:105%"><span style="font-size:9.0pt;line-height:105%;font-family:"Arial",sans-serif;color:#323232">_____________________________</span><span style="font-size:11.0pt;line-height:105%;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td width="336" valign="top" style="width:3.5in;padding:0in 5.4pt 0in 5.4pt">
<p class="MsoNormal" style="line-height:105%"><span style="font-size:9.0pt;line-height:105%;font-family:"Arial",sans-serif"><img border="0" width="115" height="46" style="width:1.1979in;height:.4791in" id="Picture_x0020_1" src="cid:image002.png@01D63340.C252AD10"></span><span style="font-size:11.0pt;line-height:105%;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td width="336" valign="top" style="width:3.5in;padding:0in 5.4pt 0in 5.4pt">
<p class="MsoNormal" style="line-height:105%"><span style="font-size:9.0pt;line-height:105%;font-family:"Arial",sans-serif;color:#323232">Lewis Roca Rothgerber Christie LLP</span><span style="font-size:11.0pt;line-height:105%;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td width="336" valign="top" style="width:3.5in;padding:0in 5.4pt 0in 5.4pt">
<p class="MsoNormal" style="line-height:105%"><span style="font-size:9.0pt;line-height:105%;font-family:"Arial",sans-serif;color:#323232">One South Church Avenue, Suite 2000</span><span style="font-size:11.0pt;line-height:105%;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td width="336" valign="top" style="width:3.5in;padding:0in 5.4pt 0in 5.4pt">
<p class="MsoNormal" style="line-height:105%"><span style="font-size:9.0pt;line-height:105%;font-family:"Arial",sans-serif;color:#323232">Tucson, Arizona 85701-1611</span><span style="font-size:11.0pt;line-height:105%;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td width="336" valign="top" style="width:3.5in;padding:0in 5.4pt 0in 5.4pt">
<p class="MsoNormal" style="line-height:105%"><span style="font-size:9.0pt;line-height:105%;font-family:"Arial",sans-serif"><a href="http://lrrc.com/" target="_new" title="Lewis Roca Rothgerber Christie Webpage"><span style="color:#AF272F">lrrc.com</span></a></span><span style="font-size:11.0pt;line-height:105%;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td width="336" valign="top" style="width:3.5in;padding:0in 5.4pt 0in 5.4pt">
<p class="MsoNormal" style="margin-top:2.0pt;line-height:105%"><span style="font-size:9.0pt;line-height:105%;font-family:"Arial",sans-serif"><img border="0" width="120" height="39" style="width:1.25in;height:.4062in" id="Picture_x0020_2" src="cid:image003.jpg@01D63340.C252AD10"></span><span style="font-size:11.0pt;line-height:105%;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td width="336" valign="top" style="width:3.5in;padding:0in 5.4pt 0in 5.4pt">
<p class="MsoNormal" style="margin-top:2.0pt;line-height:105%"><span style="font-size:10.0pt;line-height:105%;font-family:"Arial",sans-serif;color:#323232">Because what matters</span><span style="font-size:11.0pt;line-height:105%;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td width="336" valign="top" style="width:3.5in;padding:0in 5.4pt 0in 5.4pt">
<p class="MsoNormal" style="line-height:105%"><span style="font-size:10.0pt;line-height:105%;font-family:"Arial",sans-serif;color:#323232">to you, matters to us.™</span><span style="font-size:11.0pt;line-height:105%;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td width="336" valign="top" style="width:3.5in;padding:0in 5.4pt 0in 5.4pt"></td>
</tr>
</tbody>
</table>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<br>
<hr>
<font face="Arial" color="Gray" size="1"><br>
This message and any attachments are intended only for the use of the individual or entity to which they are addressed. If the reader of this message or an attachment is not the intended recipient or the employee or agent responsible for delivering the message
or attachment to the intended recipient you are hereby notified that any dissemination, distribution or copying of this message or any attachment is strictly prohibited. If you have received this communication in error, please notify us immediately by replying
to the sender. The information transmitted in this message and any attachments may be privileged, is intended only for the personal and confidential use of the intended recipients, and is covered by the Electronic Communications Privacy Act, 18 U.S.C. §2510-2521.
<br>
</font>
</body>
</html>