Landon Curt Noll
518a6336d0
By changing the _inventory_order_ of the compressed tarball from
**100000** to **1415926535**, the compressed tarball will land at
the top of the secondary file list and remain still easy to find.
Updated the `manifest.numbers` spreadsheet and rebuilt
the `.entry.json` files.
Added `next/` directory to hold the next IOCCC rules and guidelines.
Added `next/README.md` that `bin/gen-top-html.sh` uses to form
the `next/index.html` file.
Added _Rules and Guidelines_ link to the sidenav bar to link to the
`next/index.html` file.
Added _IOCCC Rules_ as `next/rules.md` that `bin/gen-top-html.sh`
uses to form the `next/rules.html` file.
Added _IOCCC Guidelines_ as `next/guidelines.md` that `bin/gen-top-html.sh`
uses to form the `next/guidelines.html` file.
Changed `bin/gen-top-html.sh` VERSION from "1.2.4 2024-04-13"
to "1.3 2024-04-14".
Prevent `pandoc(1)` from interpreting the commented out language
of a markdown code block as a code class. So a markdown such as:
````
``` <!---sh-->
...
```
````
that produced HTML of the form:
```html
<pre class="<!---sh-->"><code>...</code></pre>
```
will now produce HTML of the form:
```html
<pre><code>...</code></pre>
```
NOTE: Before when the language of a markdown code block
was not commented, the HTML produced by `pandoc(1)` was
oddly indented with extra whitespace on the first line
of the code block. While commenting out the language
of the code block removed some of the odd intending,
it left a weird class in the HTML pre block that
surrounded the HTML code block. This hack prevents
`pandoc(1)` from assigning a class to the HTML pre block.
Changed `in/md2html.sh` VERSION from "1.2.1 2024-04-13"
to "1.3 2024-04-14".
Added `make gen_sitemap` to end of both `make www` and `make
quick_www` in top level Makefile.
Ram `make www` to test under macOS and to perform the above.
**IMPORTANT NOTE**: The current `next/rules.md` and `next/guidelines.md`
are simply the 2020 IOCCC Rules and Guidelines converted into
markdown form. There are **NOT** the Rules and Guidelines that
will be used the IOCCC MOCK, nor the next IOCCC.
TODO: Improve the `bin/gen-status.sh` tool to modify the top of the
`next/rules.md` and `next/guidelines.md` files to keep them
in sync with the _contest_status_ as found in `status.json`.
TODO: Improve the look and feel of the `next/rules.md` and
`next/guidelines.md` markdown files.
269 lines
12 KiB
HTML
269 lines
12 KiB
HTML
<!DOCTYPE html>
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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
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<meta charset="utf-8">
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<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
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<title>The International Obfuscated C Code Contest</title>
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<link rel="icon" type="image/x-icon" href="../../favicon.ico">
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<meta name="description" content="compilers.md for 1986/marshall">
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<meta name="keywords" content="IOCCC, 1986/marshall, compilers.md">
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</head>
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<!-- !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! -->
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<!-- !!! Do not modify this web page, instead modify the file: 1986/marshall/compilers.md !!! -->
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<!-- !!! Do not modify this web page, instead modify the file: 1986/marshall/compilers.md !!! -->
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<body>
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<div class="header">
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<img src="../../png/ioccc.png" alt="IOCCC image by Matt Zucker" width=300 height=110>
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<h1>The International Obfuscated C Code Contest</h1>
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<h2>compilers.md for 1986/marshall</h2>
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<div class="topnav">
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<a class="Left" href="index.html">↑ jump to index.html ↑</a>
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<div class="sidenav">
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<a href="#content">Jump to contents</a>
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</div>
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<hr>
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<div class="sidenav">
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<a href="../../index.html">IOCCC Home</a>
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<a href="../../years.html">Winning Entries</a>
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<a href="../../authors.html">People who have won</a>
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<a href="../../location.html">Location of authors</a>
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</div>
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<hr>
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<div class="sidenav">
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<a href="../../news.html">IOCCC News</a>
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<a href="../../status.html">Contest status</a>
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<a href="../../next/index.html">Rules and Guidelines</a>
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<a href="../../faq.html#submit">How to enter the IOCCC</a>
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<a href="../../faq.html">FAQ</a>
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</div>
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<hr>
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<div class="sidenav">
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<a href="../../bugs.html">Bugs & (mis)features</a>
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<a href="../../faq.html#fix_an_entry">Fixing IOCCC entries</a>
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<a href="../../faq.html#fix_web_site">Fixing the web site</a>
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<a href="../../faq.html#fix_author">Fixing author info</a>
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<a href="../../thanks-for-help.html">Thanks for the help</a>
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</div>
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<hr>
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<div class="sidenav">
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<a href="../../judges.html">The IOCCC Judges</a>
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<a href="../../contact.html">Contacting the IOCCC</a>
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</div>
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<hr>
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<div class="sidenav">
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<a href="#top">Jump to top</a>
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<a name="content"></a>
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<!-- START: this line starts content for HTML phase 21 by: bin/pandoc-wrapper.sh via bin/md2html.sh -->
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<h1 id="conflicting-compilers-and-optimisers-that-broke-this-entry-in-2023">Conflicting compilers and optimisers that broke this entry in 2023</h1>
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<p>As briefly noted in the <a href="README.md">README.md</a> gcc and clang caused different
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problems with this entry depending on the optimiser being enabled or not, where
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if the optimiser was enabled it would work with one compiler and not the other.
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But if you then disabled the optimiser the opposite problem would occur: the
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working compiler would no longer work and the non-functional one would start to
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work! And then there’s the problem of linux versus macOS causing problems.</p>
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<p>The <a href="marshall.alt.c">alternate code</a> (source code) demonstrates the problem so
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you can see if your compiler has the problem as described below.</p>
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<p>In some versions of gcc and clang (this was first discovered in fedora linux 38)
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if the compiler was enabled one compiler would generate code that segfaulted but
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the other one would not. However, when then disabling the optimiser the compiler
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that had no problem suddenly did and the one that did suddenly did not. But
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segfaulting was not by any means the only problem.</p>
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<p>Another problem was that depending on the optimiser an infinite loop would be
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entered. But then removing it would cause other problems as well, including a
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segfault.</p>
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<p>It was not only one compiler that dumped core. Both dumped core with other
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behaviour, depending on what changes in code were made and the optimiser being
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on or off. Clang in macOS also dumped core!</p>
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<p>The <a href="README.md#alternate-code">alternate code</a> (README.md) has the original fix
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for clang which works with some compilers depending on the optimiser. When we
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refer to the code below we refer to the alternate code.</p>
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<h2 id="the-conflicting-compiler-problems">The conflicting compiler problems:</h2>
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<p>Below we describe the conflicting options that resulted in the need to modify
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the original code.</p>
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<h3 id="linux">Linux</h3>
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<p>With the optimiser disabled GCC compiled the code to enter an infinite loop.
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Enabling the optimiser and it worked fine. But if the optimiser is enabled clang
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generates code that first prints the text twice (it should print it once) and
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then immediately dumps core!</p>
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<p>But then there’s that infinite loop. What happens if we remove it?</p>
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<p>Once the loop is removed if we compile with clang and the optimiser is disabled
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all is okay. If however we compile with gcc and the optimiser is disabled the
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string is printed once and then the program dumps core! Why is this? It is
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because of the call to <code>_exit()</code> (see below).</p>
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<p>Clang works fine with the loop removed and the optimiser disabled. If however we
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enable the optimiser clang will generate code that prints the string twice and
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dumps core just like before! What about the call to <code>_exit()</code>?</p>
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<p>The call was:</p>
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<pre><code> _exit(argv[(int)*argc-2/cc[1*(int)*argc]|-1<<4]);</code></pre>
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<p>Changing it to not refer to these variables and just exit 1 and the problems
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disappear!</p>
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<h3 id="macos">macOS</h3>
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<p>But then there was macOS which had another problem!</p>
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<p>If the infinite loop is not removed/commented out and the optimiser is enabled
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it works fine but if it’s disabled it prints out the string and then enters an
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infinite loop!</p>
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<p>After we fix the infinite loop if we change the <code>_exit()</code> call in macOS and
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disable the optimiser we might get something like:</p>
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<pre><code> $ ./marshall
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choo choo
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Segmentation fault: 11</code></pre>
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<p>Observe how it doesn’t print it twice. But of course it segfaults so it’s not
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right either.</p>
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<p>If the optimiser is enabled, however, we will see that it works fine before the
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change to <code>_exit()</code>.</p>
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<h2 id="summary">Summary</h2>
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<p>And that is the tale of a little <strike>engine</strike> train that
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could…eventually! Or perhaps it’s the compilers, optimisers and OSes that
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eventually could?</p>
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<p>Whichever you wish it to be, it now works with both clang and gcc! Choo choo!</p>
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<!--
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Copyright © 1984-2024 by Landon Curt Noll. All Rights Reserved.
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You are free to share and adapt this file under the terms of this license:
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Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
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For more information, see:
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https://creativecommons.org/licenses/by-sa/4.0/
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-->
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<!-- END: this line ends content for HTML phase 21 by: bin/pandoc-wrapper.sh via bin/md2html.sh -->
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<!--
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Copyright © 1984-2024 by Landon Curt Noll. All Rights Reserved.
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You are free to share and adapt this file under the terms of this license:
|
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Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
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For more information, see:
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https://creativecommons.org/licenses/by-sa/4.0/
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-->
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<div class="footer">
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<h2><a name="copyright"></a>Copyright and CC BY-SA 4.0 License</h2>
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<p>All IOCCC content including this file and web page are:</p>
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<b> Copyright © 1984-2024 by Landon Curt Noll. <a href="https://creativecommons.org/faq/#what-does-some-rights-reserved-mean">Some Rights Reserved</a>.</b>
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<p>This work is licensed by Landon Curt Noll under:</p>
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<p xmlns:cc="http://creativecommons.org/ns#" ><b><a href="https://creativecommons.org/licenses/by-sa/4.0/?ref=chooser-v1"
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target="_blank" rel="license noopener noreferrer" style="display:inline-block;"> CC BY-SA 4.0
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<img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;"
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src="../../png/cc.png"
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alt="cc inside circle symbol">
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<img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;"
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src="../../png/by.png"
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alt="person inside circle symbol">
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<img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;"
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src="../../png/sa.png"
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alt="arrow looping back on itself inside circle symbol">
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</a></b></p>
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<p>The <b>CC BY-SA 4.0 LEGAL CODE</b> for this license is found under:</p>
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<p> <b><a href="https://creativecommons.org/licenses/by-sa/4.0/legalcode.en">
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https://creativecommons.org/licenses/by-sa/4.0/legalcode.en</a></b></p>
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<p>You should <b>carefully review</b> all of the terms and conditions of the
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<a href="https://creativecommons.org/licenses/by-sa/4.0/legalcode.en">actual license</a>
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before using the licensed material.</p>
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<p>You may wish to review the <b><a href="../../license.html">highlights of some of the key
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features and terms</a></b> of the <a href="https://creativecommons.org/licenses/by-sa/4.0/legalcode.en">actual license</a>.</p>
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<h2>Coda</h2>
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<p><a href="https://validator.w3.org/nu/?doc=#">Nu HTML check this web page</a></p>
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