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<p><strong>unbound</strong> <em>adj.</em> not having an associated denotation in a <span><i>binding</i></span>. See <span><i>bound</i></span>.</p>
<p><strong>unbound variable</strong> <em>n.</em> a <span><i>name</i></span> that is syntactically plausible as the name of a <span><i>variable</i></span> but which is not <span><i>bound</i></span> in the <em>variable namespace</em>.</p>
<p><strong>undefined function</strong> <em>n.</em> a <span><i>name</i></span> that is syntactically plausible as the name of a</p>
<p><span><i>function</i></span> but which is not <span><i>bound</i></span> in the <em>function namespace</em>.</p>
<p><span><b>unintern</b></span> <em>v.t.</em> (a <span><i>symbol</i></span> in a <span><i>package</i></span>) to make the <span><i>symbol</i></span> not be <span><i>present</i></span> in that <span><i>package</i></span>. (The <span><i>symbol</i></span> might continue to be <span><i>accessible</i></span> by inheritance.)</p>
<p><strong>uninterned</strong> <em>adj.</em> (of a <span><i>symbol</i></span>) not <span><i>accessible</i></span> in any <span><i>package</i></span>; <em>i.e.</em>, not <span><i>interned</i></span> <sub>1</sub>.</p>
<p><strong>universal time</strong> <em>n. time</em>, represented as a non-negative <em>integer</em> number of seconds. <em>Absolute universal time</em> is measured as an offset from the beginning of the year 1900 (ignoring <span><i>leap seconds</i></span>). See Section 25.1.4.2 (Universal Time).</p>
<p><strong>unqualified method</strong> <em>n.</em> a <span><i>method</i></span> with no <span><i>qualifiers</i></span>.</p>
<p><strong>unregistered package</strong> <em>n.</em> a <em>package object</em> that is not present in the <span><i>package</i></span></p>
<p><em>registry</em>. An <span><i>unregistered package</i></span> has no <span><i>name</i></span>; <em>i.e.</em>, its <span><i>name</i></span> is <span><b>nil</b></span>. See the <span><i>function</i></span> <span><b>delete-package</b></span>.</p>
<p><strong>unsafe</strong> <em>adj.</em> (of <span><i>code</i></span>) not <span><i>safe</i></span>. (Note that, unless explicitly specified otherwise, if a particular kind of error checking is guaranteed only in a <span><i>safe</i></span> context, the same checking might or might not occur in that context if it were <span><i>unsafe</i></span>; describing a</p>
<p>context as <span><i>unsafe</i></span> means that certain kinds of error checking are not reliably enabled but does not guarantee that error checking is definitely disabled.)</p>
<p><strong>unsafe call</strong> <em>n.</em> a <span><i>call</i></span> that is not a <span><i>safe call</i></span>. For more detailed information, see Section 3.5.1.1 (Safe and Unsafe Calls).</p>
<p><strong>upgrade</strong> <em>v.t.</em> (a declared <span><i>type</i></span> to an actual <span><i>type</i></span>) 1. (when creating an <span><i>array</i></span>)</p>
<p>to substitute an <span><i>actual array element type</i></span> for an <span><i>expressed array element type</i></span></p>
<p>when choosing an appropriately <em>specialized array</em> representation. See the <span><i>function</i></span> <span><b>upgraded-array-element-type</b></span>. 2. (when creating a <span><i>complex</i></span> ) to substitute an <span><i>actual complex part type</i></span> for an <span><i>expressed complex part type</i></span> when choosing an appropriately <em>specialized complex</em> representation. See the <span><i>function</i></span> <span><b>upgraded-complex-part-type</b></span>.</p>
<p><strong>upgraded array element type</strong> <em>n.</em> (of a <span><i>type</i></span>) a <span><i>type</i></span> that is a <span><i>supertype</i></span> of the <span><i>type</i></span> and that is used instead of the <span><i>type</i></span> whenever the <span><i>type</i></span> is used as an <span><i>array element type</i></span> for object creation or type discrimination. See Section 15.1.2.1 (Array Upgrading).</p>
<p><strong>upgraded complex part type</strong> <em>n.</em> (of a <span><i>type</i></span>) a <span><i>type</i></span> that is a <span><i>supertype</i></span> of the <span><i>type</i></span> and that is used instead of the <span><i>type</i></span> whenever the <span><i>type</i></span> is used as a <span><i>complex part type</i></span> for object creation or type discrimination. See the <span><i>function</i></span> <span><b>upgraded-complex-part-type</b></span>.</p>
<p><strong>uppercase</strong> <em>adj.</em> (of a <span><i>character</i></span> ) being among <span><i>standard characters</i></span> corresponding to the capital letters A through Z, or being some other <em>implementation-defined character</em> that is defined by the <span><i>implementation</i></span> to be <span><i>uppercase</i></span>. See Section 13.1.4.3 (Characters With Case).</p>
<p><strong>use</strong> <em>v.t.</em> (a <em>package P</em><sub>1</sub>) to <span><i>inherit</i></span> the <span><i>external symbols</i></span> of <em>P</em><sub>1</sub>. (If a package <em>P</em><sub>2</sub> uses <em>P</em><sub>1</sub>, the <span><i>external symbols</i></span> of <em>P</em><sub>1</sub> become <span><i>internal symbols</i></span> of <em>P</em><sub>2</sub> unless they are explicitly <span><i>exported</i></span>.) “The package CL-USER uses the package CL.”</p>
<p><strong>use list</strong> <em>n.</em> (of a <span><i>package</i></span>) a (possibly empty) <span><i>list</i></span> associated with each <span><i>package</i></span> which determines what other <span><i>packages</i></span> are currently being <em>used</em> by that <span><i>package</i></span>.</p>
<p><strong>user</strong> <em>n.</em> an active entity, typically a human, that invokes or interacts with a <span><i>program</i></span> at run time, but that is not necessarily a <span><i>programmer</i></span> .</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-26/u.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="t.html"><div class="pagination-nav__sublabel">Previous</div><div class="pagination-nav__label">T</div></a><a class="pagination-nav__link pagination-nav__link--next" href="v.html"><div class="pagination-nav__sublabel">Next</div><div class="pagination-nav__label">V</div></a></nav></div></div></div></div></main></div></div></div><footer class="footer footer--dark"><div class="container container-fluid"><div class="row footer__links"><div class="col footer__col"><div class="footer__title">Docs</div><ul class="footer__items clean-list"><li class="footer__item"><a href="../../docs/tutorial.html" target="_blank" rel="noopener noreferrer" class="footer__link-item">Common Lisp Tutorial</a></li><li class="footer__item"><a href="../index.html" target="_blank" rel="noopener noreferrer" class="footer__link-item">Common Lisp Technical Reference</a></li><li class="footer__item"><a href="../../docs/help.html" target="_blank" rel="noopener noreferrer" class="footer__link-item">Help</a></li></ul></div><div class="col footer__col"><div class="footer__title">Community</div><ul class="footer__items clean-list"><li class="footer__item"><a href="https://stackoverflow.com/questions/tagged/common-lisp" target="_blank" rel="noopener noreferrer" class="footer__link-item">Stack Overflow<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_nPIU"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></a></li><li class="footer__item"><a href="https://discord.gg/hhk46CE" target="_blank" rel="noopener noreferrer" class="footer__link-item">Discord<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_nPIU"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></a></li><li class="footer__item"><a href="https://www.reddit.com/r/common_lisp" target="_blank" rel="noopener noreferrer" class="footer__link-item">Reddit<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_nPIU"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></a></li><li class="footer__item"><a href="https://irclog.tymoon.eu/libera/commonlisp" target="_blank" rel="noopener noreferrer" class="footer__link-item">IRC<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_nPIU"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></a></li></ul></div><div class="col footer__col"><div class="footer__title">More</div><ul class="footer__items clean-list"><li class="footer__item"><a href="../../blog.html" target="_blank" rel="noopener noreferrer" class="footer__link-item">Blog</a></li><li 
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			`<p><strong>unbound</strong> <em>adj.</em> not having an associated denotation in a <span><i>binding</i></span>. See <span><i>bound</i></span>.</p>`
			`<p><strong>unbound variable</strong> <em>n.</em> a <span><i>name</i></span> that is syntactically plausible as the name of a <span><i>variable</i></span> but which is not <span><i>bound</i></span> in the <em>variable namespace</em>.</p>`
			`<p><strong>undefined function</strong> <em>n.</em> a <span><i>name</i></span> that is syntactically plausible as the name of a</p>`
			`<p><span><i>function</i></span> but which is not <span><i>bound</i></span> in the <em>function namespace</em>.</p>`
			`<p><span><b>unintern</b></span> <em>v.t.</em> (a <span><i>symbol</i></span> in a <span><i>package</i></span>) to make the <span><i>symbol</i></span> not be <span><i>present</i></span> in that <span><i>package</i></span>. (The <span><i>symbol</i></span> might continue to be <span><i>accessible</i></span> by inheritance.)</p>`
			`<p><strong>uninterned</strong> <em>adj.</em> (of a <span><i>symbol</i></span>) not <span><i>accessible</i></span> in any <span><i>package</i></span>; <em>i.e.</em>, not <span><i>interned</i></span> <sub>1</sub>.</p>`
			`<p><strong>universal time</strong> <em>n. time</em>, represented as a non-negative <em>integer</em> number of seconds. <em>Absolute universal time</em> is measured as an offset from the beginning of the year 1900 (ignoring <span><i>leap seconds</i></span>). See Section 25.1.4.2 (Universal Time).</p>`
			`<p><strong>unqualified method</strong> <em>n.</em> a <span><i>method</i></span> with no <span><i>qualifiers</i></span>.</p>`
			`<p><strong>unregistered package</strong> <em>n.</em> a <em>package object</em> that is not present in the <span><i>package</i></span></p>`
			`<p><em>registry</em>. An <span><i>unregistered package</i></span> has no <span><i>name</i></span>; <em>i.e.</em>, its <span><i>name</i></span> is <span><b>nil</b></span>. See the <span><i>function</i></span> <span><b>delete-package</b></span>.</p>`
			`<p><strong>unsafe</strong> <em>adj.</em> (of <span><i>code</i></span>) not <span><i>safe</i></span>. (Note that, unless explicitly specified otherwise, if a particular kind of error checking is guaranteed only in a <span><i>safe</i></span> context, the same checking might or might not occur in that context if it were <span><i>unsafe</i></span>; describing a</p>`
			`<p>context as <span><i>unsafe</i></span> means that certain kinds of error checking are not reliably enabled but does not guarantee that error checking is definitely disabled.)</p>`
			`<p><strong>unsafe call</strong> <em>n.</em> a <span><i>call</i></span> that is not a <span><i>safe call</i></span>. For more detailed information, see Section 3.5.1.1 (Safe and Unsafe Calls).</p>`
			`<p><strong>upgrade</strong> <em>v.t.</em> (a declared <span><i>type</i></span> to an actual <span><i>type</i></span>) 1. (when creating an <span><i>array</i></span>)</p>`
			`<p>to substitute an <span><i>actual array element type</i></span> for an <span><i>expressed array element type</i></span></p>`
			`<p>when choosing an appropriately <em>specialized array</em> representation. See the <span><i>function</i></span> <span><b>upgraded-array-element-type</b></span>. 2. (when creating a <span><i>complex</i></span> ) to substitute an <span><i>actual complex part type</i></span> for an <span><i>expressed complex part type</i></span> when choosing an appropriately <em>specialized complex</em> representation. See the <span><i>function</i></span> <span><b>upgraded-complex-part-type</b></span>.</p>`
			`<p><strong>upgraded array element type</strong> <em>n.</em> (of a <span><i>type</i></span>) a <span><i>type</i></span> that is a <span><i>supertype</i></span> of the <span><i>type</i></span> and that is used instead of the <span><i>type</i></span> whenever the <span><i>type</i></span> is used as an <span><i>array element type</i></span> for object creation or type discrimination. See Section 15.1.2.1 (Array Upgrading).</p>`
			`<p><strong>upgraded complex part type</strong> <em>n.</em> (of a <span><i>type</i></span>) a <span><i>type</i></span> that is a <span><i>supertype</i></span> of the <span><i>type</i></span> and that is used instead of the <span><i>type</i></span> whenever the <span><i>type</i></span> is used as a <span><i>complex part type</i></span> for object creation or type discrimination. See the <span><i>function</i></span> <span><b>upgraded-complex-part-type</b></span>.</p>`
			`<p><strong>uppercase</strong> <em>adj.</em> (of a <span><i>character</i></span> ) being among <span><i>standard characters</i></span> corresponding to the capital letters A through Z, or being some other <em>implementation-defined character</em> that is defined by the <span><i>implementation</i></span> to be <span><i>uppercase</i></span>. See Section 13.1.4.3 (Characters With Case).</p>`
			`<p><strong>use</strong> <em>v.t.</em> (a <em>package P</em><sub>1</sub>) to <span><i>inherit</i></span> the <span><i>external symbols</i></span> of <em>P</em><sub>1</sub>. (If a package <em>P</em><sub>2</sub> uses <em>P</em><sub>1</sub>, the <span><i>external symbols</i></span> of <em>P</em><sub>1</sub> become <span><i>internal symbols</i></span> of <em>P</em><sub>2</sub> unless they are explicitly <span><i>exported</i></span>.) “The package CL-USER uses the package CL.”</p>`
			`<p><strong>use list</strong> <em>n.</em> (of a <span><i>package</i></span>) a (possibly empty) <span><i>list</i></span> associated with each <span><i>package</i></span> which determines what other <span><i>packages</i></span> are currently being <em>used</em> by that <span><i>package</i></span>.</p>`
			<p><strong>user</strong> <em>n.</em> an active entity, typically a human, that invokes or interacts with a <span><i>program</i></span> at run time, but that is not necessarily a <span><i>programmer</i></span> .</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-26/u.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="t.html"><div class="pagination-nav__sublabel">Previous</div><div class="pagination-nav__label">T</div></a><a class="pagination-nav__link pagination-nav__link--next" href="v.html"><div class="pagination-nav__sublabel">Next</div><div class="pagination-nav__label">V</div></a></nav></div></div></div></div></main></div></div></div><footer class="footer footer--dark"><div class="container container-fluid"><div class="row footer__links"><div class="col footer__col"><div class="footer__title">Docs</div><ul class="footer__items clean-list"><li class="footer__item"><a href="../../docs/tutorial.html" target="_blank" rel="noopener noreferrer" class="footer__link-item">Common Lisp Tutorial</a></li><li class="footer__item"><a href="../index.html" target="_blank" rel="noopener noreferrer" class="footer__link-item">Common Lisp Technical Reference</a></li><li class="footer__item"><a href="../../docs/help.html" target="_blank" rel="noopener noreferrer" class="footer__link-item">Help</a></li></ul></div><div class="col footer__col"><div class="footer__title">Community</div><ul class="footer__items clean-list"><li class="footer__item"><a href="https://stackoverflow.com/questions/tagged/common-lisp" target="_blank" rel="noopener noreferrer" class="footer__link-item">Stack Overflow<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_nPIU"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></a></li><li class="footer__item"><a href="https://discord.gg/hhk46CE" target="_blank" rel="noopener noreferrer" class="footer__link-item">Discord<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_nPIU"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></a></li><li class="footer__item"><a href="https://www.reddit.com/r/common_lisp" target="_blank" rel="noopener noreferrer" class="footer__link-item">Reddit<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_nPIU"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></a></li><li class="footer__item"><a href="https://irclog.tymoon.eu/libera/commonlisp" target="_blank" rel="noopener noreferrer" class="footer__link-item">IRC<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_nPIU"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></a></li></ul></div><div class="col footer__col"><div class="footer__title">More</div><ul class="footer__items clean-list"><li class="footer__item"><a href="../../blog.html" target="_blank" rel="noopener noreferrer" class="footer__link-item">Blog</a></li><li
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