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<h2 class="anchor anchorWithStickyNavbar_LWe7" id="1311-introduction-to-characters">13.1.1 Introduction to Characters<a href="bd-b-character-concepts.html#1311-introduction-to-characters" class="hash-link" aria-label="Direct link to 13.1.1 Introduction to Characters" title="Direct link to 13.1.1 Introduction to Characters"></a></h2>
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<p>A <span><i>character</i></span> is an <span><i>object</i></span> that represents a unitary token (<em>e.g.</em>, a letter, a special symbol, or a “control character”) in an aggregate quantity of text (<em>e.g.</em>, a <span><i>string</i></span> or a text <span><i>stream</i></span>).</p>
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<p>Common Lisp allows an implementation to provide support for international language <span><i>characters</i></span> as well as <span><i>characters</i></span> used in specialized arenas (<em>e.g.</em>, mathematics).</p>
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<p>The following figures contain lists of <span><i>defined names</i></span> applicable to <span><i>characters</i></span>.</p>
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<p>Figure 13–1 lists some <span><i>defined names</i></span> relating to <em>character attributes</em> and <em>character predicates</em>.</p>
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<p>|</p><p><strong>alpha-char-p char-not-equal char</strong>> </p><p><strong>alphanumericp char-not-greaterp char</strong>><span><b>=</b></span> </p><p><strong>both-case-p char-not-lessp digit-char-p</strong> </p><p><strong>char-code-limit char/= graphic-char-p char-equal char</strong>< <span><b>lower-case-p</b></span> </p><p><strong>char-greaterp char</strong><<strong>= standard-char-p char-lessp char= upper-case-p</strong></p>|<p></p>
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<p>| :- |</p>
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<p><strong>Figure 13–1. Character defined names – 1</strong></p>
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<p>Figure 13–2 lists some <span><i>character</i></span> construction and conversion <span><i>defined names</i></span>.</p>
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<p>|</p><p><strong>char-code char-name code-char</strong> </p><p><strong>char-downcase char-upcase digit-char</strong> </p><p><strong>char-int character name-char</strong></p>|<p></p>
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<p>| :- |</p>
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<p><strong>Figure 13–2. Character defined names – 2</strong></p>
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<h2 class="anchor anchorWithStickyNavbar_LWe7" id="1312-introduction-to-scripts-and-repertoires">13.1.2 Introduction to Scripts and Repertoires<a href="bd-b-character-concepts.html#1312-introduction-to-scripts-and-repertoires" class="hash-link" aria-label="Direct link to 13.1.2 Introduction to Scripts and Repertoires" title="Direct link to 13.1.2 Introduction to Scripts and Repertoires"></a></h2>
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<h3 class="anchor anchorWithStickyNavbar_LWe7" id="13121-character-scripts">13.1.2.1 Character Scripts<a href="bd-b-character-concepts.html#13121-character-scripts" class="hash-link" aria-label="Direct link to 13.1.2.1 Character Scripts" title="Direct link to 13.1.2.1 Character Scripts"></a></h3>
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<p>A <span><i>script</i></span> is one of possibly several sets that form an <span><i>exhaustive partition</i></span> of the type <span><b>character</b></span>.</p>
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<p>The number of such sets and boundaries between them is <span><i>implementation-defined</i></span>. Common Lisp does not require these sets to be <span><i>types</i></span>, but an <span><i>implementation</i></span> is permitted to define such <span><i>types</i></span> as an extension. Since no <span><i>character</i></span> from one <span><i>script</i></span> can ever be a member of another <span><i>script</i></span>, it is generally more useful to speak about <em>character repertoires</em>.</p>
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<p>Although the term “<span><i>script</i></span>” is chosen for definitional compatibility with ISO terminology, no <span><i>conforming implementation</i></span> is required to use any particular <span><i>scripts</i></span> standardized by ISO or by any other standards organization.</p>
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<p>Whether and how the <span><i>script</i></span> or <span><i>scripts</i></span> used by any given <span><i>implementation</i></span> are named is <span><i>implementation-dependent</i></span>.</p>
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<h3 class="anchor anchorWithStickyNavbar_LWe7" id="13122-character-repertoires">13.1.2.2 Character Repertoires<a href="bd-b-character-concepts.html#13122-character-repertoires" class="hash-link" aria-label="Direct link to 13.1.2.2 Character Repertoires" title="Direct link to 13.1.2.2 Character Repertoires"></a></h3>
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<p>A <span><i>repertoire</i></span> is a <span><i>type specifier</i></span> for a <span><i>subtype</i></span> of <span><i>type</i></span> <span><b>character</b></span>. This term is generally used when describing a collection of <span><i>characters</i></span> independent of their coding. <span><i>Characters</i></span> in <span><i>repertoires</i></span> are only identified by name, by <span><i>glyph</i></span>, or by character description.</p>
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<p>A <span><i>repertoire</i></span> can contain <span><i>characters</i></span> from several <span><i>scripts</i></span>, and a <span><i>character</i></span> can appear in more than one <span><i>repertoire</i></span>.</p>
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<p>For some examples of <span><i>repertoires</i></span>, see the coded character standards ISO 8859/1, ISO 8859/2, and ISO 6937/2. Note, however, that although the term “<span><i>repertoire</i></span>” is chosen for definitional compatibility with ISO terminology, no <span><i>conforming implementation</i></span> is required to use <span><i>repertoires</i></span> standardized by ISO or any other standards organization.</p>
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<h2 class="anchor anchorWithStickyNavbar_LWe7" id="1313-character-attributes">13.1.3 Character Attributes<a href="bd-b-character-concepts.html#1313-character-attributes" class="hash-link" aria-label="Direct link to 13.1.3 Character Attributes" title="Direct link to 13.1.3 Character Attributes"></a></h2>
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<p><span><i>Characters</i></span> have only one <em>standardized attribute</em>: a <span><i>code</i></span>. A <span><i>character</i></span> ’s <span><i>code</i></span> is a non-negative <em>integer</em> . This <span><i>code</i></span> is composed from a character <span><i>script</i></span> and a character label in an <em>implementation dependent</em> way. See the <span><i>functions</i></span> <span><b>char-code</b></span> and <span><b>code-char</b></span>.</p>
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<p>Additional, <em>implementation-defined attributes</em> of <span><i>characters</i></span> are also permitted so that, for example, two <span><i>characters</i></span> with the same <span><i>code</i></span> may differ in some other, <span><i>implementation-defined</i></span> way.</p>
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<p>For any <em>implementation-defined attribute</em> there is a distinguished value called the <span><i>null</i></span> value for that <span><i>attribute</i></span>. A <span><i>character</i></span> for which each <em>implementation-defined attribute</em> has the null value for that <span><i>attribute</i></span> is called a <em>simple character</em> . If the <span><i>implementation</i></span> has no <em>implementation-defined attributes</em>, then all <span><i>characters</i></span> are <em>simple characters</em>.</p>
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<h2 class="anchor anchorWithStickyNavbar_LWe7" id="1314-character-categories">13.1.4 Character Categories<a href="bd-b-character-concepts.html#1314-character-categories" class="hash-link" aria-label="Direct link to 13.1.4 Character Categories" title="Direct link to 13.1.4 Character Categories"></a></h2>
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<p>There are several (overlapping) categories of <span><i>characters</i></span> that have no formally associated <span><i>type</i></span> but that are nevertheless useful to name. They include <em>graphic characters</em>, <span><i>alphabetic</i></span><sub>1</sub> <span><i>characters</i></span>, <span><i>characters</i></span> with <span><i>case</i></span> (<span><i>uppercase</i></span> and <em>lowercase characters</em>), <em>numeric characters</em>, <em>alphanumeric characters</em>, and <span><i>digits</i></span> (in a given <span><i>radix</i></span> ).</p>
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<p>For each <em>implementation-defined attribute</em> of a <span><i>character</i></span> , the documentation for that <em>implementa tion</em> must specify whether <span><i>characters</i></span> that differ only in that <span><i>attribute</i></span> are permitted to differ in whether are not they are members of one of the aforementioned categories.</p>
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<p>Note that these terms are defined independently of any special syntax which might have been enabled in the <span><i>current readtable</i></span>.</p>
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<h3 class="anchor anchorWithStickyNavbar_LWe7" id="13141-graphic-characters">13.1.4.1 Graphic Characters<a href="bd-b-character-concepts.html#13141-graphic-characters" class="hash-link" aria-label="Direct link to 13.1.4.1 Graphic Characters" title="Direct link to 13.1.4.1 Graphic Characters"></a></h3>
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<p><span><i>Characters</i></span> that are classified as <span><i>graphic</i></span>, or displayable, are each associated with a glyph, a visual representation of the <span><i>character</i></span> .</p>
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<p>A <em>graphic character</em> is one that has a standard textual representation as a single <span><i>glyph</i></span>, such as A or * or =. <span><i>Space</i></span>, which effectively has a blank <span><i>glyph</i></span>, is defined to be a <span><i>graphic</i></span>.</p>
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<p>Of the <span><i>standard characters</i></span>, <span><i>newline</i></span> is <span><i>non-graphic</i></span> and all others are <span><i>graphic</i></span>; see Section 2.1.3 (Standard Characters).</p>
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<p><span><i>Characters</i></span> that are not <span><i>graphic</i></span> are called <span><i>non-graphic</i></span>. <em>Non-graphic characters</em> are sometimes informally called “formatting characters” or “control characters.”</p>
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<p>#\Backspace, #\Tab, #\Rubout, #\Linefeed, #\Return, and #\Page, if they are supported by the <em>implementation</em>, are <em>non-graphic</em>.</p>
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<h3 class="anchor anchorWithStickyNavbar_LWe7" id="13142-alphabetic-characters">13.1.4.2 Alphabetic Characters<a href="bd-b-character-concepts.html#13142-alphabetic-characters" class="hash-link" aria-label="Direct link to 13.1.4.2 Alphabetic Characters" title="Direct link to 13.1.4.2 Alphabetic Characters"></a></h3>
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<p>The <span><i>alphabetic</i></span><sub>1</sub> <span><i>characters</i></span> are a subset of the <em>graphic characters</em>. Of the <span><i>standard characters</i></span>, only these are the <span><i>alphabetic</i></span><sub>1</sub> <span><i>characters</i></span>:</p>
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<p>A B C D E F G H I J K L M N O P Q R S T U V W X Y Z</p>
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<p>a b c d e f g h i j k l m n o p q r s t u v w x y z</p>
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<p>Any <i>implementation-defined character</i> that has <i>case</i> must be <i>alphabetic</i><sub>1</sub><sup>. For each <i>implementation</i></sup> defined graphic character that has no <i>case</i>, it is <i>implementation-defined</i> whether that <i>character</i> is <i>alphabetic</i><sub>1</sub>.</p>
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<h3 class="anchor anchorWithStickyNavbar_LWe7" id="13143-characters-with-case">13.1.4.3 Characters With Case<a href="bd-b-character-concepts.html#13143-characters-with-case" class="hash-link" aria-label="Direct link to 13.1.4.3 Characters With Case" title="Direct link to 13.1.4.3 Characters With Case"></a></h3>
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<p>The <span><i>characters</i></span> with <span><i>case</i></span> are a subset of the <span><i>alphabetic</i></span><sub>1</sub> <span><i>characters</i></span>. A <span><i>character</i></span> with <span><i>case</i></span> has the property of being either <span><i>uppercase</i></span> or <span><i>lowercase</i></span>. Every <span><i>character</i></span> with <span><i>case</i></span> is in one-to-one correspondence with some other <span><i>character</i></span> with the opposite <span><i>case</i></span>.</p>
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<h4 class="anchor anchorWithStickyNavbar_LWe7" id="131431-uppercase-characters">13.1.4.3.1 Uppercase Characters<a href="bd-b-character-concepts.html#131431-uppercase-characters" class="hash-link" aria-label="Direct link to 13.1.4.3.1 Uppercase Characters" title="Direct link to 13.1.4.3.1 Uppercase Characters"></a></h4>
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<p>An uppercase <span><i>character</i></span> is one that has a corresponding <em>lowercase character</em> that is <span><i>different</i></span> (and can be obtained using <span><b>char-downcase</b></span>).</p>
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<p>Of the <span><i>standard characters</i></span>, only these are <em>uppercase characters</em>:</p>
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<p>A B C D E F G H I J K L M N O P Q R S T U V W X Y Z</p>
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<h4 class="anchor anchorWithStickyNavbar_LWe7" id="131432-lowercase-characters">13.1.4.3.2 Lowercase Characters<a href="bd-b-character-concepts.html#131432-lowercase-characters" class="hash-link" aria-label="Direct link to 13.1.4.3.2 Lowercase Characters" title="Direct link to 13.1.4.3.2 Lowercase Characters"></a></h4>
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<p>A lowercase <span><i>character</i></span> is one that has a corresponding <em>uppercase character</em> that is <span><i>different</i></span> (and can be obtained using <span><b>char-upcase</b></span>).</p>
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<p>Of the <span><i>standard characters</i></span>, only these are <em>lowercase characters</em>:</p>
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<p>a b c d e f g h i j k l m n o p q r s t u v w x y z</p>
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<h4 class="anchor anchorWithStickyNavbar_LWe7" id="131433-corresponding-characters-in-the-other-case">13.1.4.3.3 Corresponding Characters in the Other Case<a href="bd-b-character-concepts.html#131433-corresponding-characters-in-the-other-case" class="hash-link" aria-label="Direct link to 13.1.4.3.3 Corresponding Characters in the Other Case" title="Direct link to 13.1.4.3.3 Corresponding Characters in the Other Case"></a></h4>
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<p>The <em>uppercase standard characters</em> A through Z mentioned above respectively correspond to the <em>lowercase standard characters</em> a through z mentioned above. For example, the <em>uppercase character</em> E corresponds to the <em>lowercase character</em> e, and vice versa.</p>
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<h4 class="anchor anchorWithStickyNavbar_LWe7" id="131434-case-of-implementation">13.1.4.3.4 Case of Implementation<a href="bd-b-character-concepts.html#131434-case-of-implementation" class="hash-link" aria-label="Direct link to 13.1.4.3.4 Case of Implementation" title="Direct link to 13.1.4.3.4 Case of Implementation"></a></h4>
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<p>An <span><i>implementation</i></span> may define that other <em>implementation-defined graphic characters</em> have <span><i>case</i></span>. Such definitions must always be done in pairs—one <em>uppercase character</em> in one-to-one <em>correspondence</em> with one <em>lowercase character</em> .</p>
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<h3 class="anchor anchorWithStickyNavbar_LWe7" id="13144-numeric-characters">13.1.4.4 Numeric Characters<a href="bd-b-character-concepts.html#13144-numeric-characters" class="hash-link" aria-label="Direct link to 13.1.4.4 Numeric Characters" title="Direct link to 13.1.4.4 Numeric Characters"></a></h3>
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<p>The <em>numeric characters</em> are a subset of the <em>graphic characters</em>. Of the <span><i>standard characters</i></span>, only these are <em>numeric characters</em>:</p>
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<p>0 1 2 3 4 5 6 7 8 9</p>
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<p>For each <em>implementation-defined graphic character</em> that has no <span><i>case</i></span>, the <span><i>implementation</i></span> must define whether or not it is a <em>numeric character</em> .</p>
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<h3 class="anchor anchorWithStickyNavbar_LWe7" id="13145-alphanumeric-characters">13.1.4.5 Alphanumeric Characters<a href="bd-b-character-concepts.html#13145-alphanumeric-characters" class="hash-link" aria-label="Direct link to 13.1.4.5 Alphanumeric Characters" title="Direct link to 13.1.4.5 Alphanumeric Characters"></a></h3>
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<p>The set of <em>alphanumeric characters</em> is the union of the set of <span><i>alphabetic</i></span><sub>1</sub> <span><i>characters</i></span> and the set of <em>numeric characters</em>.</p>
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<h3 class="anchor anchorWithStickyNavbar_LWe7" id="13146-digits-in-a-radix">13.1.4.6 Digits in a Radix<a href="bd-b-character-concepts.html#13146-digits-in-a-radix" class="hash-link" aria-label="Direct link to 13.1.4.6 Digits in a Radix" title="Direct link to 13.1.4.6 Digits in a Radix"></a></h3>
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<p>What qualifies as a <span><i>digit</i></span> depends on the <span><i>radix</i></span> (an <em>integer</em> between 2 and 36, inclusive). The potential <span><i>digits</i></span> are:</p>
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<p>0 1 2 3 4 5 6 7 8 9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z</p>
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<p>Their respective weights are 0, 1, 2, <em>. . .</em> 35. In any given radix <em>n</em>, only the first <em>n</em> potential <span><i>digits</i></span> are considered to be <span><i>digits</i></span>. For example, the digits in radix 2 are 0 and 1, the digits in radix 10 are 0 through 9, and the digits in radix 16 are 0 through F.</p>
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<p><span><i>Case</i></span> is not significant in <span><i>digits</i></span>; for example, in radix 16, both F and f are <span><i>digits</i></span> with weight 15.</p>
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<h2 class="anchor anchorWithStickyNavbar_LWe7" id="1315-identity-of-characters">13.1.5 Identity of Characters<a href="bd-b-character-concepts.html#1315-identity-of-characters" class="hash-link" aria-label="Direct link to 13.1.5 Identity of Characters" title="Direct link to 13.1.5 Identity of Characters"></a></h2>
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<p>Two <span><i>characters</i></span> that are <span><b>eql</b></span>, <span><b>char=</b></span>, or <span><b>char-equal</b></span> are not necessarily <span><b>eq</b></span>.</p>
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<h2 class="anchor anchorWithStickyNavbar_LWe7" id="1316-ordering-of-characters">13.1.6 Ordering of Characters<a href="bd-b-character-concepts.html#1316-ordering-of-characters" class="hash-link" aria-label="Direct link to 13.1.6 Ordering of Characters" title="Direct link to 13.1.6 Ordering of Characters"></a></h2>
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<p>The total ordering on <span><i>characters</i></span> is guaranteed to have the following properties:</p>
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<p><em>•</em> If two <span><i>characters</i></span> have the same <em>implementation-defined attributes</em>, then their ordering by <span><b>char</b></span>< is consistent with the numerical ordering by the predicate < on their code <span><i>attributes</i></span>.</p>
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<p><em>•</em> If two <span><i>characters</i></span> differ in any <span><i>attribute</i></span>, then they are not <span><b>char=</b></span>.</p>
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<p><em>•</em> The total ordering is not necessarily the same as the total ordering on the <em>integers</em> produced by applying <span><b>char-int</b></span> to the <span><i>characters</i></span>.</p>
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<p><em>•</em> While <span><i>alphabetic</i></span><sub>1</sub> <span><i>standard characters</i></span> of a given <span><i>case</i></span> must obey a partial ordering, they need not be contiguous; it is permissible for <span><i>uppercase</i></span> and <em>lowercase characters</em> to be interleaved. Thus <code>(char<= #\a x #\z)</code> is not a valid way of determining whether or not x is a <em>lowercase character</em> .</p>
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<p>Of the <span><i>standard characters</i></span>, those which are <span><i>alphanumeric</i></span> obey the following partial ordering:</p>
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<ul>
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<li><code>A<B<C<D<E<F<G<H<I<J<K<L<M<N<O<P<Q<R<S<T<U<V<W<X<Y<Z</code></li>
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<li><code>a<b<c<d<e<f<g<h<i<j<k<l<m<n<o<p<q<r<s<t<u<v<w<x<y<z</code></li>
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<li><code>0<1<2<3<4<5<6<7<8<9</code></li>
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<li>either <code>9<A</code> or <code>Z<0</code></li>
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<li>either <code>9<a</code> or <code>z<0</code></li>
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</ul>
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<p>This implies that, for <span><i>standard characters</i></span>, <span><i>alphabetic</i></span><sup><a href="bd-b-character-concepts.html#user-content-fn-1" id="user-content-fnref-1" data-footnote-ref="true" aria-describedby="footnote-label">1</a></sup> ordering holds within each <span><i>case</i></span> (<span><i>uppercase</i></span> and <span><i>lowercase</i></span>), and that the <em>numeric characters</em> as a group are not interleaved with <em>alphabetic characters</em>. However, the ordering or possible interleaving of <em>uppercase characters</em> and <em>lowercase characters</em> is <span><i>implementation-defined</i></span>.</p>
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<div class="theme-admonition theme-admonition-warning admonition_xJq3 alert alert--warning"><div class="admonitionHeading_Gvgb"><span class="admonitionIcon_Rf37"><svg viewBox="0 0 16 16"><path fill-rule="evenodd" d="M8.893 1.5c-.183-.31-.52-.5-.887-.5s-.703.19-.886.5L.138 13.499a.98.98 0 0 0 0 1.001c.193.31.53.501.886.501h13.964c.367 0 .704-.19.877-.5a1.03 1.03 0 0 0 .01-1.002L8.893 1.5zm.133 11.497H6.987v-2.003h2.039v2.003zm0-3.004H6.987V5.987h2.039v4.006z"></path></svg></span>warning</div><div class="admonitionContent_BuS1"><p>We have a missing footnote "<span><i>alphabetic</i></span><sup><a href="bd-b-character-concepts.html#user-content-fn-1" id="user-content-fnref-1-2" data-footnote-ref="true" aria-describedby="footnote-label">1</a></sup>" from the specification. Please help us find it!</p></div></div>
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<section data-footnotes="true" class="footnotes"><h2 class="anchor anchorWithStickyNavbar_LWe7 sr-only" id="footnote-label">Footnotes<a href="bd-b-character-concepts.html#footnote-label" class="hash-link" aria-label="Direct link to Footnotes" title="Direct link to Footnotes"></a></h2>
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<ol>
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<li id="user-content-fn-1">
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<p>Unclear where this footnote is in the specification <a href="bd-b-character-concepts.html#user-content-fnref-1" data-footnote-backref="" aria-label="Back to reference 1" class="data-footnote-backref">↩</a> <a href="bd-b-character-concepts.html#user-content-fnref-1-2" data-footnote-backref="" aria-label="Back to reference 1-2" class="data-footnote-backref">↩<sup>2</sup></a></p>
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</li>
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</ol>
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</section>
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<h2 class="anchor anchorWithStickyNavbar_LWe7" id="1317-character-names">13.1.7 Character Names<a href="bd-b-character-concepts.html#1317-character-names" class="hash-link" aria-label="Direct link to 13.1.7 Character Names" title="Direct link to 13.1.7 Character Names"></a></h2>
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<p>The following <em>character names</em> must be present in all <span><i>conforming implementations</i></span>:</p>
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<p>Newline</p>
|
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<p>The character that represents the division between lines. An implementation must translate between #\Newline, a single-character representation, and whatever external representation(s) may be used.</p>
|
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<p>Space</p>
|
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<p>The space or blank character.</p>
|
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<p>The following names are <span><i>semi-standard</i></span>; if an <span><i>implementation</i></span> supports them, they should be used for the described <span><i>characters</i></span> and no others.</p>
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<p>Rubout</p>
|
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<p>The rubout or delete character.</p>
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<p>Page</p>
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<p>The form-feed or page-separator character.</p>
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<p>Tab</p>
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<p>The tabulate character.</p>
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<p>Backspace</p>
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<p>The backspace character.</p>
|
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<p>Return</p>
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<p>The carriage return character.</p>
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<p>Linefeed</p>
|
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<p>The line-feed character.</p>
|
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<p>In some <span><i>implementations</i></span>, one or more of these <em>character names</em> might denote a <span><i>standard character</i></span> ; for example, #\Linefeed and #\Newline might be the <em>same character</em> in some <span><i>implementations</i></span>.</p>
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<h2 class="anchor anchorWithStickyNavbar_LWe7" id="1318-treatment-of-newline-during-input-and-output">13.1.8 Treatment of Newline during Input and Output<a href="bd-b-character-concepts.html#1318-treatment-of-newline-during-input-and-output" class="hash-link" aria-label="Direct link to 13.1.8 Treatment of Newline during Input and Output" title="Direct link to 13.1.8 Treatment of Newline during Input and Output"></a></h2>
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<p>When the character #\Newline is written to an output file, the implementation must take the appropriate action to produce a line division. This might involve writing out a record or translating #\Newline to a CR/LF sequence. When reading, a corresponding reverse transformation must take place.</p>
|
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<h2 class="anchor anchorWithStickyNavbar_LWe7" id="1319-character-encodings">13.1.9 Character Encodings<a href="bd-b-character-concepts.html#1319-character-encodings" class="hash-link" aria-label="Direct link to 13.1.9 Character Encodings" title="Direct link to 13.1.9 Character Encodings"></a></h2>
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<p>A <span><i>character</i></span> is sometimes represented merely by its <span><i>code</i></span>, and sometimes by another <em>integer</em> value which is composed from the <span><i>code</i></span> and all <em>implementation-defined attributes</em> (in an <em>implementation defined</em> way that might vary between <em>Lisp images</em> even in the same <span><i>implementation</i></span>). This <em>integer</em> , returned by the function <span><b>char-int</b></span>, is called the character’s “encoding.” There is no corresponding function from a character’s encoding back to the <span><i>character</i></span> , since its primary intended uses include things like hashing where an inverse operation is not really called for.</p>
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<h2 class="anchor anchorWithStickyNavbar_LWe7" id="13110-documentation-of-implementation">13.1.10 Documentation of Implementation<a href="bd-b-character-concepts.html#13110-documentation-of-implementation" class="hash-link" aria-label="Direct link to 13.1.10 Documentation of Implementation" title="Direct link to 13.1.10 Documentation of Implementation"></a></h2>
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<p>An <span><i>implementation</i></span> must document the <em>character scripts</em> it supports. For each <em>character script</em> supported, the documentation must describe at least the following:</p>
|
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<p><em>•</em> Character labels, glyphs, and descriptions. Character labels must be uniquely named using only Latin capital letters A–Z, hyphen (-), and digits 0–9.</p>
|
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<p><em>•</em> Reader canonicalization. Any mechanisms by which <span><b>read</b></span> treats <span><i>different</i></span> characters as equivalent must be documented.</p>
|
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<p><em>•</em> The impact on <span><b>char-upcase</b></span>, <span><b>char-downcase</b></span>, and the case-sensitive <span><i>format directives</i></span>. In particular, for each <span><i>character</i></span> with <span><i>case</i></span>, whether it is <span><i>uppercase</i></span> or <span><i>lowercase</i></span>, and which <span><i>character</i></span> is its equivalent in the opposite case.</p>
|
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<p><em>•</em> The behavior of the case-insensitive <span><i>functions</i></span> <span><b>char-equal</b></span>, <span><b>char-not-equal</b></span>, <span><b>char-lessp</b></span>, <span><b>char-greaterp</b></span>, <span><b>char-not-greaterp</b></span>, and <span><b>char-not-lessp</b></span>.</p>
|
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<p><em>•</em> The behavior of any <em>character predicates</em>; in particular, the effects of <span><b>alpha-char-p</b></span>, <span><b>lower-case-p</b></span>, <span><b>upper-case-p</b></span>, <span><b>both-case-p</b></span>, <span><b>graphic-char-p</b></span>, and <span><b>alphanumericp</b></span>.</p>
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<p><em>•</em> The interaction with file I/O, in particular, the supported coded character sets (for example, ISO8859/1-1987) and external encoding schemes supported are documented.</p></div><footer class="theme-doc-footer docusaurus-mt-lg"><div class="theme-doc-footer-edit-meta-row row"><div class="col"><a href="https://github.com/lisp-docs/cl-language-reference/tree/main/docs/chap-13/bd-b-character-concepts.md" target="_blank" rel="noopener noreferrer" class="theme-edit-this-page"><svg fill="currentColor" height="20" width="20" viewBox="0 0 40 40" class="iconEdit_Z9Sw" aria-hidden="true"><g><path d="m34.5 11.7l-3 3.1-6.3-6.3 3.1-3q0.5-0.5 1.2-0.5t1.1 0.5l3.9 3.9q0.5 0.4 0.5 1.1t-0.5 1.2z m-29.5 17.1l18.4-18.5 6.3 6.3-18.4 18.4h-6.3v-6.2z"></path></g></svg>Edit this page</a></div><div class="col lastUpdated_vwxv"><span class="theme-last-updated">Last updated<!-- --> by <b>daninus14</b></span></div></div></footer></article><nav class="pagination-nav docusaurus-mt-lg" aria-label="Docs pages"><a class="pagination-nav__link pagination-nav__link--prev" href="../chap-12/bc-c-dictionary/zerop_function.html"><div class="pagination-nav__sublabel">Previous</div><div class="pagination-nav__label">zerop</div></a><a class="pagination-nav__link pagination-nav__link--next" href="../category/132-characters-dictionary.html"><div class="pagination-nav__sublabel">Next</div><div class="pagination-nav__label">13.2 Characters Dictionary</div></a></nav></div></div><div class="col col--3"><div class="tableOfContents_bqdL thin-scrollbar theme-doc-toc-desktop"><ul class="table-of-contents table-of-contents__left-border"><li><a href="bd-b-character-concepts.html#1311-introduction-to-characters" class="table-of-contents__link toc-highlight">13.1.1 Introduction to Characters</a></li><li><a href="bd-b-character-concepts.html#1312-introduction-to-scripts-and-repertoires" class="table-of-contents__link toc-highlight">13.1.2 Introduction to Scripts and Repertoires</a><ul><li><a href="bd-b-character-concepts.html#13121-character-scripts" class="table-of-contents__link toc-highlight">13.1.2.1 Character Scripts</a></li><li><a href="bd-b-character-concepts.html#13122-character-repertoires" class="table-of-contents__link toc-highlight">13.1.2.2 Character Repertoires</a></li></ul></li><li><a href="bd-b-character-concepts.html#1313-character-attributes" class="table-of-contents__link toc-highlight">13.1.3 Character Attributes</a></li><li><a href="bd-b-character-concepts.html#1314-character-categories" class="table-of-contents__link toc-highlight">13.1.4 Character Categories</a><ul><li><a href="bd-b-character-concepts.html#13141-graphic-characters" class="table-of-contents__link toc-highlight">13.1.4.1 Graphic Characters</a></li><li><a href="bd-b-character-concepts.html#13142-alphabetic-characters" class="table-of-contents__link toc-highlight">13.1.4.2 Alphabetic Characters</a></li><li><a href="bd-b-character-concepts.html#13143-characters-with-case" class="table-of-contents__link toc-highlight">13.1.4.3 Characters With Case</a><ul><li><a href="bd-b-character-concepts.html#131431-uppercase-characters" class="table-of-contents__link toc-highlight">13.1.4.3.1 Uppercase Characters</a></li><li><a href="bd-b-character-concepts.html#131432-lowercase-characters" class="table-of-contents__link toc-highlight">13.1.4.3.2 Lowercase Characters</a></li><li><a href="bd-b-character-concepts.html#131433-corresponding-characters-in-the-other-case" class="table-of-contents__link toc-highlight">13.1.4.3.3 Corresponding Characters in the Other Case</a></li><li><a href="bd-b-character-concepts.html#131434-case-of-implementation" class="table-of-contents__link toc-highlight">13.1.4.3.4 Case of Implementation</a></li></ul></li><li><a href="bd-b-character-concepts.html#13144-numeric-characters" class="table-of-contents__link toc-highlight">13.1.4.4 Numeric Characters</a></li><li><a href="bd-b-character-concepts.html#13145-alphanumeric-characters" class="table-of-contents__link toc-highlight">13.1.4.5 Alphanumeric Characters</a></li><li><a href="bd-b-character-concepts.html#13146-di
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