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      <div class="breadcrumb"><a href="/">Home</a> » <a href="/licenses">Licenses</a></div>

      <h1 property="dc:title">SOFA Software License</h1>
      <div style="display:none;"><code property="spdx:deprecated">false</code></div>
      <h2>Full name</h2>
          <p style="margin-left: 20px;"><code property="spdx:name">SOFA Software License</code></p>

      <h2>Short identifier</h2>
          <p style="margin-left: 20px;"><code property="spdx:licenseId">SOFA</code></p>

      <h2>Other web pages for this license</h2>
          <div style="margin-left: 20px;">
            <ul>
             <li>
               <a href="http://www.iausofa.org/tandc.html" rel="rdfs:seeAlso" isValid=true isLive=true isWayBackLink=false match=true timestamp=2025-07-01T14:58:14Z>http://www.iausofa.org/tandc.html</a>
               <!--Tentative way of displaying information <p>isValid: true, isLive: true, isWayBackLink: false, match: true, timestamp: 2025-07-01T14:58:14Z</p> -->
             </li>
           </ul>
          </div>

      <div property="spdx:isOsiApproved" style="display: none;">false</div>

      <h2 id="notes">Notes</h2>
          <p style="margin-left: 20px;">None</p>

      <h2 id="licenseText">Text</h2>
      
      <blockquote cite="https://spdx.github.io/spdx-spec/v2.3/license-matching-guidelines-and-templates/">
          <div style="border: 2px solid grey; padding: 8px">
		      Text in italicized blue is omittable (see <a href="https://spdx.github.io/spdx-spec/v2.3/license-matching-guidelines-and-templates/#b35-guideline-omittable-text">Matching Guidelines B.3.5</a>).
		      License or exception text will match to the text for the specified identifier if it either includes or excludes this omittable text.
			  <br/>
			  <br/>
			  Text in red is replaceable (see <a href="https://spdx.github.io/spdx-spec/v2.3/license-matching-guidelines-and-templates/#b34-guideline-replaceable-text">Matching Guidelines B.3.4</a>).
			  License or exception text will match to the text for the specified identifier if it includes a permitted variant of this replaceable text.
			  The permitted variants can be found in the corresponding regular expression as shown in title text visible by hovering over the red text.
	      </div>
	  </blockquote>

      <div property="spdx:licenseText" class="license-text">
      
         <var class="replaceable-license-text"><span title="can be replaced with the pattern .{0,5000}"> 
            Copyright (C) 2023 Standards of Fundamental Astronomy
            Board of the International Astronomical Union.
         </span></var>
         <var class="optional-license-text"> 
            SOFA Software License
         </var>
         <var class="optional-license-text"> 
            NOTICE TO USER:
         </var>
         <p>
            BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING
            SIX TERMS AND CONDITIONS WHICH APPLY TO ITS USE.
         </p>

<ul style="list-style:none">
            
<li>
               <var class="replaceable-license-text"><span title="can be replaced with the pattern .{0,20}"> 1.</span></var>
               The Software is owned by the IAU SOFA Board (&quot;SOFA&quot;).
            </li>
            
<li>
               <var class="replaceable-license-text"><span title="can be replaced with the pattern .{0,20}"> 2.</span></var>
               Permission is granted to anyone to use the SOFA software
               for any purpose, including commercial applications,
               free of charge and without payment of royalties,
               subject to the conditions and restrictions listed below.
            </li>
            
<li>
               <var class="replaceable-license-text"><span title="can be replaced with the pattern .{0,20}"> 3.</span></var>
               You (the user) may copy and distribute SOFA source code to
               others, and use and adapt its code and algorithms in your
               own software, on a world-wide, royalty-free basis. That
               portion of your distribution that does not consist of intact
               and unchanged copies of SOFA source code files is a &quot;derived
               work&quot; that must comply with the following requirements:
               
<ul style="list-style:none">
                  
<li>
                     <var class="replaceable-license-text"><span title="can be replaced with the pattern .{0,20}"> a)</span></var>
                     Your work shall be marked or carry a statement that
                     it (i) uses routines and computations derived by
                     you from software provided by SOFA under license
                     to you; and (ii) does not itself constitute
                     software provided by and/or endorsed by SOFA.
                  </li>
                  
<li>
                     <var class="replaceable-license-text"><span title="can be replaced with the pattern .{0,20}"> b)</span></var>
                     The source code of your derived work must contain
                     descriptions of how the derived work is based upon,
                     contains and/or differs from the original SOFA software.
                  </li>
                  
<li>
                     <var class="replaceable-license-text"><span title="can be replaced with the pattern .{0,20}"> c)</span></var>
                     The names of all routines in your derived work shall
                     not include the prefix &quot;iau&quot; or &quot;sofa&quot; or trivial
                     modifications thereof such as changes of case.
                  </li>
                  
<li>
                     <var class="replaceable-license-text"><span title="can be replaced with the pattern .{0,20}"> d)</span></var>
                     The origin of the SOFA components of your derived work must
                     not be misrepresented; you must not claim that you wrote
                     the original software, nor file a patent application for
                     SOFA software or algorithms embedded in the SOFA software.
                  </li>
                  
<li>
                     <var class="replaceable-license-text"><span title="can be replaced with the pattern .{0,20}"> e)</span></var>
                     These requirements must be reproduced intact
                     in any source distribution and shall apply to
                     anyone to whom you have granted a further right
                     to modify the source code of your derived work.
                  </li>
               
</ul>
               <p>
                  Note that, as originally distributed, the SOFA software
                  is intended to be a definitive implementation of the IAU
                  standards, and consequently third-party modifications
                  are discouraged. All variations, no matter how minor,
                  must be explicitly marked as such, as explained above.
               </p>

            </li>
            
<li>
               <var class="replaceable-license-text"><span title="can be replaced with the pattern .{0,20}"> 4.</span></var>
               You shall not cause the SOFA software to be brought
               into disrepute, either by misuse, or use for
               inappropriate tasks, or by inappropriate modification.
            </li>
            
<li>
               <var class="replaceable-license-text"><span title="can be replaced with the pattern .{0,20}"> 5.</span></var>
               The SOFA software is provided &quot;as is&quot; and SOFA makes no
               warranty as to its use or performance. SOFA does not and cannot
               warrant the performance or results which the user may obtain
               by using the SOFA software. SOFA makes no warranties, express
               or implied, as to non-infringement of third party rights,
               merchantability, or fitness for any particular purpose. In no
               event will SOFA be liable to the user for any consequential,
               incidental, or special damages, including any lost profits
               or lost savings, even if a SOFA representative has been
               advised of such damages, or for any claim by any third party.
            </li>
            
<li>
               <var class="replaceable-license-text"><span title="can be replaced with the pattern .{0,20}"> 6.</span></var>
               The provision of any version of the SOFA software
               under the terms and conditions specified herein
               does not imply that future versions will also be
               made available under the same terms and conditions.
            </li>
         
</ul>
         <div class="optional-license-text"> 
<p>In any published work or commercial product which uses the SOFA
  software directly, acknowledgement (see www.iausofa.org) is
  appreciated.</p>

<p>  Correspondence concerning SOFA software should be addressed as
  follows:</p>

     <p> By email:  sofa@ukho.gov.uk
    <br />
  By post:   IAU SOFA Center
     <br />
            HM Nautical Almanac Office
     <br />
            UK Hydrographic Office
     <br />
            Admiralty Way, Taunton
     <br />
            Somerset, TA1 2DN
      <br />
           United Kingdom</p>

         </div>
      
      </div>

      <h2  id="licenseHeader">Standard License Header</h2>
      <div property="spdx:standardLicenseHeader" class="license-text">
        <p style="font-style: italic">There is no standard license header for the license</p>
        
      </div>
      <div property="spdx:standardLicenseTemplate" style="display: none;">
      &lt;&lt;var;name&#61;&quot;copyright&quot;;original&#61;&quot;Copyright (C) 2023 Standards of Fundamental Astronomy Board of the International Astronomical Union.&quot;;match&#61;&quot;.{0,5000}&quot;&gt;&gt;&lt;&lt;beginOptional&gt;&gt; SOFA Software License&lt;&lt;endOptional&gt;&gt;&lt;&lt;beginOptional&gt;&gt; NOTICE TO USER:&lt;&lt;endOptional&gt;&gt;&#10;BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND CONDITIONS WHICH APPLY TO ITS USE.&#10;&#10;   &lt;&lt;var;name&#61;&quot;bullet&quot;;original&#61;&quot;1.&quot;;match&#61;&quot;.{0,20}&quot;&gt;&gt; The Software is owned by the IAU SOFA Board (&quot;SOFA&quot;).&#10;   &lt;&lt;var;name&#61;&quot;bullet&quot;;original&#61;&quot;2.&quot;;match&#61;&quot;.{0,20}&quot;&gt;&gt; Permission is granted to anyone to use the SOFA software for any purpose, including commercial applications, free of charge and without payment of royalties, subject to the conditions and restrictions listed below.&#10;   &lt;&lt;var;name&#61;&quot;bullet&quot;;original&#61;&quot;3.&quot;;match&#61;&quot;.{0,20}&quot;&gt;&gt; You (the user) may copy and distribute SOFA source code to others, and use and adapt its code and algorithms in your own software, on a world-wide, royalty-free basis. That portion of your distribution that does not consist of intact and unchanged copies of SOFA source code files is a &quot;derived work&quot; that must comply with the following requirements:&#10;      &lt;&lt;var;name&#61;&quot;bullet&quot;;original&#61;&quot;a)&quot;;match&#61;&quot;.{0,20}&quot;&gt;&gt; Your work shall be marked or carry a statement that it (i) uses routines and computations derived by you from software provided by SOFA under license to you; and (ii) does not itself constitute software provided by and/or endorsed by SOFA.&#10;      &lt;&lt;var;name&#61;&quot;bullet&quot;;original&#61;&quot;b)&quot;;match&#61;&quot;.{0,20}&quot;&gt;&gt; The source code of your derived work must contain descriptions of how the derived work is based upon, contains and/or differs from the original SOFA software.&#10;      &lt;&lt;var;name&#61;&quot;bullet&quot;;original&#61;&quot;c)&quot;;match&#61;&quot;.{0,20}&quot;&gt;&gt; The names of all routines in your derived work shall not include the prefix &quot;iau&quot; or &quot;sofa&quot; or trivial modifications thereof such as changes of case.&#10;      &lt;&lt;var;name&#61;&quot;bullet&quot;;original&#61;&quot;d)&quot;;match&#61;&quot;.{0,20}&quot;&gt;&gt; The origin of the SOFA components of your derived work must not be misrepresented; you must not claim that you wrote the original software, nor file a patent application for SOFA software or algorithms embedded in the SOFA software.&#10;      &lt;&lt;var;name&#61;&quot;bullet&quot;;original&#61;&quot;e)&quot;;match&#61;&quot;.{0,20}&quot;&gt;&gt; These requirements must be reproduced intact in any source distribution and shall apply to anyone to whom you have granted a further right to modify the source code of your derived work.&#10;   Note that, as originally distributed, the SOFA software is intended to be a definitive implementation of the IAU standards, and consequently third-party modifications are discouraged. All variations, no matter how minor, must be explicitly marked as such, as explained above.&#10;&#10;   &lt;&lt;var;name&#61;&quot;bullet&quot;;original&#61;&quot;4.&quot;;match&#61;&quot;.{0,20}&quot;&gt;&gt; You shall not cause the SOFA software to be brought into disrepute, either by misuse, or use for inappropriate tasks, or by inappropriate modification.&#10;   &lt;&lt;var;name&#61;&quot;bullet&quot;;original&#61;&quot;5.&quot;;match&#61;&quot;.{0,20}&quot;&gt;&gt; The SOFA software is provided &quot;as is&quot; and SOFA makes no warranty as to its use or performance. SOFA does not and cannot warrant the performance or results which the user may obtain by using the SOFA software. SOFA makes no warranties, express or implied, as to non-infringement of third party rights, merchantability, or fitness for any particular purpose. In no event will SOFA be liable to the user for any consequential, incidental, or special damages, including any lost profits or lost savings, even if a SOFA representative has been advised of such damages, or for any claim by any third party.&#10;   &lt;&lt;var;name&#61;&quot;bullet&quot;;original&#61;&quot;6.&quot;;match&#61;&quot;.{0,20}&quot;&gt;&gt; The provision of any version of the SOFA software under the terms and conditions specified herein does not imply that future versions will also be made available under the same terms and conditions.&lt;&lt;beginOptional&gt;&gt; In any published work or commercial product which uses the SOFA software directly, acknowledgement (see www.iausofa.org) is appreciated.&#10;&#10;Correspondence concerning SOFA software should be addressed as follows:&#10;&#10;By email: sofa@ukho.gov.uk&#10;By post: IAU SOFA Center&#10;HM Nautical Almanac Office&#10;UK Hydrographic Office&#10;Admiralty Way, Taunton&#10;Somerset, TA1 2DN&#10;United Kingdom&#10;&#10;&lt;&lt;endOptional&gt;&gt;
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