75 lines
3.7 KiB
HTML
75 lines
3.7 KiB
HTML
<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|
<html>
|
|
<!--
|
|
|
|
Generated from r6rs.tex by tex2page, v 20100828
|
|
(running on MzScheme 4.2.4, :unix),
|
|
(c) Dorai Sitaram,
|
|
http://evalwhen.com/tex2page/index.html
|
|
|
|
-->
|
|
<head>
|
|
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
|
|
<title>
|
|
Revised^6 Report on the Algorithmic Language Scheme
|
|
</title>
|
|
<link rel="stylesheet" type="text/css" href="r6rs-Z-S.css" title=default>
|
|
<meta name=robots content="index,follow">
|
|
</head>
|
|
<body>
|
|
<div id=slidecontent>
|
|
<div align=right class=navigation>[Go to <span><a href="r6rs.html">first</a>, <a href="r6rs-Z-H-4.html">previous</a></span><span>, <a href="r6rs-Z-H-6.html">next</a></span> page<span>; </span><span><a href="r6rs-Z-H-2.html#node_toc_start">contents</a></span><span><span>; </span><a href="r6rs-Z-H-21.html#node_index_start">index</a></span>]</div>
|
|
<p></p>
|
|
<a name="node_chap_2"></a>
|
|
<h1 class=chapter>
|
|
<div class=chapterheading><a href="r6rs-Z-H-2.html#node_toc_node_chap_2">Chapter 2</a></div><br>
|
|
<a href="r6rs-Z-H-2.html#node_toc_node_chap_2">Requirement levels</a></h1>
|
|
<p></p>
|
|
<p>
|
|
The key words “must”, “must not”, “should”,
|
|
“should not”, “recommended”, “may”, and “optional” in this
|
|
report are to be interpreted as described in RFC 2119 [<a href="r6rs-Z-H-21.html#node_bib_3">3</a>].
|
|
Specifically:</p>
|
|
<p>
|
|
</p>
|
|
<dl><dt></dt><dd>
|
|
</dd><dt><b>must</b></dt><dd><a name="node_idx_64"></a>This word means that a statement is an absolute
|
|
requirement of the specification.
|
|
</dd><dt><b>must not</b></dt><dd><a name="node_idx_66"></a>This phrase means that a statement is an absolute
|
|
prohibition of the specification.
|
|
</dd><dt><b>should</b></dt><dd><a name="node_idx_68"></a>This word, or the adjective “recommended”, means that
|
|
valid reasons may exist in particular circumstances to ignore a
|
|
statement, but that the implications must be understood and weighed
|
|
before choosing a different course.
|
|
</dd><dt><b>should not</b></dt><dd><a name="node_idx_70"></a>This phrase, or the phrase “not recommended”, means
|
|
that valid reasons may exist in particular circumstances when the
|
|
behavior of a statement is acceptable, but that the implications
|
|
should be understood and weighed before choosing the course described
|
|
by the statement.
|
|
</dd><dt><b>may</b></dt><dd><a name="node_idx_72"></a>This word, or the adjective “optional”, means that an item
|
|
is truly optional.
|
|
</dd></dl><p></p>
|
|
<p>
|
|
In particular, this report occasionally uses “should” to designate
|
|
circumstances that are outside the specification of this report, but
|
|
cannot be practically detected by an implementation; see
|
|
section <a href="r6rs-Z-H-8.html#node_sec_5.4">5.4</a>. In such circumstances, a
|
|
particular implementation may allow the programmer to ignore the
|
|
recommendation of the report and even exhibit reasonable behavior.
|
|
However, as the report does not specify the behavior,
|
|
these programs may be unportable, that is, their execution might
|
|
produce different results on different implementations.</p>
|
|
<p>
|
|
Moreover, this report occasionally uses the phrase “not required” to note the
|
|
absence of an absolute requirement.</p>
|
|
<p>
|
|
</p>
|
|
<p></p>
|
|
<div class=smallskip></div>
|
|
<p style="margin-top: 0pt; margin-bottom: 0pt">
|
|
<div align=right class=navigation>[Go to <span><a href="r6rs.html">first</a>, <a href="r6rs-Z-H-4.html">previous</a></span><span>, <a href="r6rs-Z-H-6.html">next</a></span> page<span>; </span><span><a href="r6rs-Z-H-2.html#node_toc_start">contents</a></span><span><span>; </span><a href="r6rs-Z-H-21.html#node_index_start">index</a></span>]</div>
|
|
</p>
|
|
<p></p>
|
|
</div>
|
|
</body>
|
|
</html>
|