858 lines
24 KiB
HTML
858 lines
24 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
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"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
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<head>
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<meta http-equiv="Content-Type" content="application/xhtml+xml; charset=UTF-8" />
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<meta name="generator" content="AsciiDoc 8.6.9" />
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<title>Extracting music from Modulae</title>
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<style type="text/css">
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/* Shared CSS for AsciiDoc xhtml11 and html5 backends */
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/* Default font. */
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body {
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font-family: Georgia,serif;
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}
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/* Title font. */
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h1, h2, h3, h4, h5, h6,
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div.title, caption.title,
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thead, p.table.header,
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#toctitle,
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#author, #revnumber, #revdate, #revremark,
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#footer {
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font-family: Arial,Helvetica,sans-serif;
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}
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body {
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margin: 1em 5% 1em 5%;
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}
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a {
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color: blue;
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text-decoration: underline;
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}
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a:visited {
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color: fuchsia;
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}
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em {
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font-style: italic;
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color: navy;
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}
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strong {
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font-weight: bold;
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color: #083194;
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}
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h1, h2, h3, h4, h5, h6 {
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color: #527bbd;
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margin-top: 1.2em;
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margin-bottom: 0.5em;
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line-height: 1.3;
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}
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h1, h2, h3 {
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border-bottom: 2px solid silver;
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}
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h2 {
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padding-top: 0.5em;
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}
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h3 {
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float: left;
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}
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h3 + * {
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clear: left;
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}
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h5 {
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font-size: 1.0em;
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}
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div.sectionbody {
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margin-left: 0;
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}
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hr {
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border: 1px solid silver;
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}
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p {
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margin-top: 0.5em;
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margin-bottom: 0.5em;
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}
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ul, ol, li > p {
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margin-top: 0;
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}
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ul > li { color: #aaa; }
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ul > li > * { color: black; }
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.monospaced, code, pre {
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font-family: "Courier New", Courier, monospace;
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font-size: inherit;
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color: navy;
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padding: 0;
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margin: 0;
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}
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pre {
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white-space: pre-wrap;
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}
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#author {
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color: #527bbd;
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font-weight: bold;
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font-size: 1.1em;
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}
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#email {
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}
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#revnumber, #revdate, #revremark {
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}
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#footer {
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font-size: small;
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border-top: 2px solid silver;
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padding-top: 0.5em;
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margin-top: 4.0em;
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}
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#footer-text {
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float: left;
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padding-bottom: 0.5em;
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}
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#footer-badges {
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float: right;
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padding-bottom: 0.5em;
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}
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#preamble {
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margin-top: 1.5em;
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margin-bottom: 1.5em;
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}
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div.imageblock, div.exampleblock, div.verseblock,
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div.quoteblock, div.literalblock, div.listingblock, div.sidebarblock,
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div.admonitionblock {
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margin-top: 1.0em;
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margin-bottom: 1.5em;
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}
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div.admonitionblock {
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margin-top: 2.0em;
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margin-bottom: 2.0em;
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margin-right: 10%;
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color: #606060;
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}
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div.content { /* Block element content. */
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padding: 0;
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}
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/* Block element titles. */
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div.title, caption.title {
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color: #527bbd;
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font-weight: bold;
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text-align: left;
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margin-top: 1.0em;
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margin-bottom: 0.5em;
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}
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div.title + * {
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margin-top: 0;
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}
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td div.title:first-child {
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margin-top: 0.0em;
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}
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div.content div.title:first-child {
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margin-top: 0.0em;
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}
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div.content + div.title {
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margin-top: 0.0em;
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}
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div.sidebarblock > div.content {
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background: #ffffee;
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border: 1px solid #dddddd;
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border-left: 4px solid #f0f0f0;
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padding: 0.5em;
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}
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div.listingblock > div.content {
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border: 1px solid #dddddd;
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border-left: 5px solid #f0f0f0;
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background: #f8f8f8;
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padding: 0.5em;
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}
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div.quoteblock, div.verseblock {
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padding-left: 1.0em;
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margin-left: 1.0em;
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margin-right: 10%;
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border-left: 5px solid #f0f0f0;
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color: #888;
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}
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div.quoteblock > div.attribution {
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padding-top: 0.5em;
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text-align: right;
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}
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div.verseblock > pre.content {
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font-family: inherit;
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font-size: inherit;
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}
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div.verseblock > div.attribution {
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padding-top: 0.75em;
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text-align: left;
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}
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/* DEPRECATED: Pre version 8.2.7 verse style literal block. */
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div.verseblock + div.attribution {
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text-align: left;
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}
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div.admonitionblock .icon {
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vertical-align: top;
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font-size: 1.1em;
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font-weight: bold;
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text-decoration: underline;
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color: #527bbd;
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padding-right: 0.5em;
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}
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div.admonitionblock td.content {
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padding-left: 0.5em;
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border-left: 3px solid #dddddd;
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}
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div.exampleblock > div.content {
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border-left: 3px solid #dddddd;
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padding-left: 0.5em;
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}
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div.imageblock div.content { padding-left: 0; }
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span.image img { border-style: none; vertical-align: text-bottom; }
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a.image:visited { color: white; }
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dl {
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margin-top: 0.8em;
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margin-bottom: 0.8em;
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}
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dt {
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margin-top: 0.5em;
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margin-bottom: 0;
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font-style: normal;
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color: navy;
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}
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dd > *:first-child {
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margin-top: 0.1em;
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}
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ul, ol {
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list-style-position: outside;
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}
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ol.arabic {
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list-style-type: decimal;
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}
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ol.loweralpha {
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list-style-type: lower-alpha;
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}
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ol.upperalpha {
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list-style-type: upper-alpha;
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}
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ol.lowerroman {
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list-style-type: lower-roman;
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}
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ol.upperroman {
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list-style-type: upper-roman;
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}
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div.compact ul, div.compact ol,
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div.compact p, div.compact p,
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div.compact div, div.compact div {
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margin-top: 0.1em;
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margin-bottom: 0.1em;
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}
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tfoot {
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font-weight: bold;
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}
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td > div.verse {
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white-space: pre;
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}
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div.hdlist {
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margin-top: 0.8em;
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margin-bottom: 0.8em;
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}
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div.hdlist tr {
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padding-bottom: 15px;
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}
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dt.hdlist1.strong, td.hdlist1.strong {
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font-weight: bold;
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}
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td.hdlist1 {
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vertical-align: top;
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font-style: normal;
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padding-right: 0.8em;
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color: navy;
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}
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td.hdlist2 {
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vertical-align: top;
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}
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div.hdlist.compact tr {
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margin: 0;
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padding-bottom: 0;
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}
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.comment {
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background: yellow;
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}
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.footnote, .footnoteref {
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font-size: 0.8em;
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}
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span.footnote, span.footnoteref {
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vertical-align: super;
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}
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#footnotes {
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margin: 20px 0 20px 0;
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padding: 7px 0 0 0;
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}
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#footnotes div.footnote {
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margin: 0 0 5px 0;
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}
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#footnotes hr {
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border: none;
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border-top: 1px solid silver;
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height: 1px;
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text-align: left;
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margin-left: 0;
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width: 20%;
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min-width: 100px;
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}
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div.colist td {
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padding-right: 0.5em;
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padding-bottom: 0.3em;
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vertical-align: top;
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}
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div.colist td img {
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margin-top: 0.3em;
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}
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@media print {
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#footer-badges { display: none; }
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}
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#toc {
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margin-bottom: 2.5em;
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}
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#toctitle {
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color: #527bbd;
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font-size: 1.1em;
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font-weight: bold;
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margin-top: 1.0em;
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margin-bottom: 0.1em;
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}
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div.toclevel0, div.toclevel1, div.toclevel2, div.toclevel3, div.toclevel4 {
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margin-top: 0;
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margin-bottom: 0;
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}
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div.toclevel2 {
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margin-left: 2em;
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font-size: 0.9em;
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}
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div.toclevel3 {
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margin-left: 4em;
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font-size: 0.9em;
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}
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div.toclevel4 {
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margin-left: 6em;
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font-size: 0.9em;
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}
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span.aqua { color: aqua; }
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span.black { color: black; }
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span.blue { color: blue; }
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span.fuchsia { color: fuchsia; }
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span.gray { color: gray; }
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span.green { color: green; }
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span.lime { color: lime; }
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span.maroon { color: maroon; }
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span.navy { color: navy; }
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span.olive { color: olive; }
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span.purple { color: purple; }
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span.red { color: red; }
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span.silver { color: silver; }
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span.teal { color: teal; }
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span.white { color: white; }
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span.yellow { color: yellow; }
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span.aqua-background { background: aqua; }
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span.black-background { background: black; }
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span.blue-background { background: blue; }
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span.fuchsia-background { background: fuchsia; }
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span.gray-background { background: gray; }
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span.green-background { background: green; }
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span.lime-background { background: lime; }
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span.maroon-background { background: maroon; }
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span.navy-background { background: navy; }
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span.olive-background { background: olive; }
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span.purple-background { background: purple; }
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span.red-background { background: red; }
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span.silver-background { background: silver; }
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span.teal-background { background: teal; }
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span.white-background { background: white; }
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span.yellow-background { background: yellow; }
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span.big { font-size: 2em; }
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span.small { font-size: 0.6em; }
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span.underline { text-decoration: underline; }
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span.overline { text-decoration: overline; }
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span.line-through { text-decoration: line-through; }
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div.unbreakable { page-break-inside: avoid; }
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/*
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* xhtml11 specific
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*
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* */
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div.tableblock {
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margin-top: 1.0em;
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margin-bottom: 1.5em;
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}
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div.tableblock > table {
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border: 3px solid #527bbd;
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}
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thead, p.table.header {
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font-weight: bold;
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color: #527bbd;
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}
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p.table {
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margin-top: 0;
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}
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/* Because the table frame attribute is overriden by CSS in most browsers. */
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div.tableblock > table[frame="void"] {
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border-style: none;
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}
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div.tableblock > table[frame="hsides"] {
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border-left-style: none;
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border-right-style: none;
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}
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div.tableblock > table[frame="vsides"] {
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border-top-style: none;
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border-bottom-style: none;
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}
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/*
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* html5 specific
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*
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* */
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table.tableblock {
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margin-top: 1.0em;
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margin-bottom: 1.5em;
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}
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thead, p.tableblock.header {
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font-weight: bold;
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color: #527bbd;
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}
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p.tableblock {
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margin-top: 0;
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}
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table.tableblock {
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border-width: 3px;
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border-spacing: 0px;
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border-style: solid;
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border-color: #527bbd;
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border-collapse: collapse;
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}
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th.tableblock, td.tableblock {
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border-width: 1px;
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padding: 4px;
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border-style: solid;
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border-color: #527bbd;
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}
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table.tableblock.frame-topbot {
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border-left-style: hidden;
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border-right-style: hidden;
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}
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table.tableblock.frame-sides {
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border-top-style: hidden;
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border-bottom-style: hidden;
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}
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table.tableblock.frame-none {
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border-style: hidden;
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}
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th.tableblock.halign-left, td.tableblock.halign-left {
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text-align: left;
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}
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th.tableblock.halign-center, td.tableblock.halign-center {
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text-align: center;
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}
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th.tableblock.halign-right, td.tableblock.halign-right {
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text-align: right;
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}
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th.tableblock.valign-top, td.tableblock.valign-top {
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vertical-align: top;
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}
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th.tableblock.valign-middle, td.tableblock.valign-middle {
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vertical-align: middle;
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}
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th.tableblock.valign-bottom, td.tableblock.valign-bottom {
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vertical-align: bottom;
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}
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/*
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* manpage specific
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*
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* */
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body.manpage h1 {
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padding-top: 0.5em;
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padding-bottom: 0.5em;
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border-top: 2px solid silver;
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border-bottom: 2px solid silver;
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}
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body.manpage h2 {
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border-style: none;
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}
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body.manpage div.sectionbody {
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margin-left: 3em;
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}
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@media print {
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body.manpage div#toc { display: none; }
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}
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</style>
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<script type="text/javascript">
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/*<+'])');
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// Function that scans the DOM tree for header elements (the DOM2
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// nodeIterator API would be a better technique but not supported by all
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// browsers).
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var iterate = function (el) {
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for (var i = el.firstChild; i != null; i = i.nextSibling) {
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if (i.nodeType == 1 /* Node.ELEMENT_NODE */) {
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var mo = re.exec(i.tagName);
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if (mo && (i.getAttribute("class") || i.getAttribute("className")) != "float") {
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result[result.length] = new TocEntry(i, getText(i), mo[1]-1);
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}
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iterate(i);
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}
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}
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}
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iterate(el);
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return result;
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}
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var toc = document.getElementById("toc");
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if (!toc) {
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return;
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}
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// Delete existing TOC entries in case we're reloading the TOC.
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var tocEntriesToRemove = [];
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var i;
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for (i = 0; i < toc.childNodes.length; i++) {
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var entry = toc.childNodes[i];
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if (entry.nodeName.toLowerCase() == 'div'
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&& entry.getAttribute("class")
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&& entry.getAttribute("class").match(/^toclevel/))
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tocEntriesToRemove.push(entry);
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}
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for (i = 0; i < tocEntriesToRemove.length; i++) {
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toc.removeChild(tocEntriesToRemove[i]);
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}
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// Rebuild TOC entries.
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var entries = tocEntries(document.getElementById("content"), toclevels);
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for (var i = 0; i < entries.length; ++i) {
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var entry = entries[i];
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if (entry.element.id == "")
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entry.element.id = "_toc_" + i;
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var a = document.createElement("a");
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a.href = "#" + entry.element.id;
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</head>
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<body class="article">
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<div id="header">
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<h1>Extracting music from Modulae</h1>
|
|
</div>
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<div id="content">
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|
<div id="preamble">
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|
<div class="sectionbody">
|
|
<div class="paragraph"><p>This is a walkthrough for how I located and extracted the music from FTA’s
|
|
Modulae demo, straight from the 2mg disk image.</p></div>
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|
<div class="paragraph"><p>We’ll begin by disassembling the boot block. The boot block is the first
|
|
block on disk, and is always loaded into <code>$0800</code>.</p></div>
|
|
<div class="listingblock">
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|
<div class="content"><!-- Generator: GNU source-highlight 3.1.8
|
|
by Lorenzo Bettini
|
|
http://www.lorenzobettini.it
|
|
http://www.gnu.org/software/src-highlite -->
|
|
<pre><tt><span style="color: #990000">.</span>/disasm modulae<span style="color: #990000">.</span>2mg <span style="color: #993399">800</span> <span style="color: #993399">0</span> <span style="color: #993399">1</span> <span style="color: #990000">></span> boot<span style="color: #990000">.</span>s</tt></pre></div></div>
|
|
<div class="paragraph"><p>This command says to extract one 512-byte block starting at block 0, into memory
|
|
location <code>$800</code> and disassemble it.</p></div>
|
|
<div class="paragraph"><p>If we analyze the disassembled boot block, we will see that the function at
|
|
<code>$08f9</code> loads a block from disk. Following that backward, we discover that
|
|
at <code>$08c9</code>, it loads blocks 7—13 into RAM starting at <code>$9400</code>. Then it
|
|
calls a function at <code>$0a00</code> and passes it the address of the RAM it just loaded.</p></div>
|
|
<div class="paragraph"><p>Blocks 7—13 contain the main loader, it’s a routine responsible for
|
|
loading the rest of the disk into various parts of RAM. The call to
|
|
<code>$0a00</code> decrunches the loader. To help with that, I built a tool that can
|
|
properly decrunch those blocks.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content"><!-- Generator: GNU source-highlight 3.1.8
|
|
by Lorenzo Bettini
|
|
http://www.lorenzobettini.it
|
|
http://www.gnu.org/software/src-highlite -->
|
|
<pre><tt><span style="color: #990000">.</span>/decrunch modulae<span style="color: #990000">.</span>2mg <span style="color: #993399">7</span> <span style="color: #993399">6</span> loader</tt></pre></div></div>
|
|
<div class="paragraph"><p>This basically extracts 6 blocks from the disk image, starting at block 7. It
|
|
decrunches them, and saves the result into a file called <code>loader</code>.</p></div>
|
|
<div class="paragraph"><p>Now we can disassemble the loader.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content"><!-- Generator: GNU source-highlight 3.1.8
|
|
by Lorenzo Bettini
|
|
http://www.lorenzobettini.it
|
|
http://www.gnu.org/software/src-highlite -->
|
|
<pre><tt><span style="color: #990000">.</span>/disasm loader <span style="color: #993399">9400</span> <span style="color: #990000">></span> loader<span style="color: #990000">.</span>s</tt></pre></div></div>
|
|
<div class="paragraph"><p>The <code>disasm</code> command will disassemble the entire file if the offset and size
|
|
arguements are omitted. It also will work on a byte-level if the file passed
|
|
isn’t a 2mg disk image.</p></div>
|
|
<div class="paragraph"><p>We remember from the previous disassembly that these blocks should be
|
|
loaded into RAM at <code>$9400</code>, so we pass that address to <code>disasm</code>.</p></div>
|
|
<div class="paragraph"><p>Now we inspect the loader disassembly. After a bit of inspection, we can
|
|
see that the main loading is done at <code>$9ad6</code>. It uses a table of addresses
|
|
located at <code>$9bad</code> to determine which blocks to load and where in RAM to put
|
|
them. It then later runs the decruncher (still at <code>$0a00</code>) on various blocks
|
|
of RAM.</p></div>
|
|
<div class="paragraph"><p>This table is the thing we care about. The first word is the starting
|
|
block on disk, which is followed by a bunch of 8-byte records. The first
|
|
dword of each record is the target address, the second dword is the number
|
|
of 256-byte pages to load. It loads these sequentially from the disk,
|
|
beginning at the starting block. It ends when a record is 0 pages long.</p></div>
|
|
<div class="paragraph"><p>I built a <code>dumptbl</code> tool that makes it easier to parse this table into
|
|
human readable format, telling us which blocks to load and where. We can
|
|
then choose to inspect the various blocks, one by one and determine which
|
|
ones we care about.</p></div>
|
|
<div class="paragraph"><p>The table we want to dump is at <code>$9bad</code>, we need to calculate that
|
|
position relative to the start of the file to determine its disk offset.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$9bad - $9400 = $07ad</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>Thus, we call <code>dumptbl</code> with the following:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content"><!-- Generator: GNU source-highlight 3.1.8
|
|
by Lorenzo Bettini
|
|
http://www.lorenzobettini.it
|
|
http://www.gnu.org/software/src-highlite -->
|
|
<pre><tt><span style="color: #990000">.</span>/dumptbl loader 7ad</tt></pre></div></div>
|
|
<div class="paragraph"><p>(Note how we pass <code>loader</code> which is the unpacked binary, and not
|
|
<code>loader.s</code> which is the disassembly).</p></div>
|
|
<div class="paragraph"><p>Using this table, we can inspect various blocks.</p></div>
|
|
<div class="paragraph"><p>The very first entry in the table is actually interesting. It consists of
|
|
58 blocks, starting at block 16 on disk, uncrunched. If we look at this
|
|
data, it’s actually the “And now, FTA Presents…” raw audio data.
|
|
It’s stored as an unsigned 8-bit PCM data. It’s in mono, and should
|
|
be played back at 11,025 Hz. I went ahead and slapped a <code>.wav</code> header
|
|
onto the audio data to save it for posterity. You’ll find it in the
|
|
songs/modulae folder.</p></div>
|
|
<div class="paragraph"><p>I also found a music player. Starting at block 801, 27 blocks are loaded
|
|
into <code>$1000</code>.</p></div>
|
|
<div class="paragraph"><p>The music player uses a wavebank loaded into <code>$9:0000</code>, and music data at
|
|
<code>$a:0400</code>. Sure enough, we can find those blocks in the table used by the main
|
|
loader. The music data is crunched, the sound data isn’t.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content"><!-- Generator: GNU source-highlight 3.1.8
|
|
by Lorenzo Bettini
|
|
http://www.lorenzobettini.it
|
|
http://www.gnu.org/software/src-highlite -->
|
|
<pre><tt><span style="color: #990000">.</span>/decrunch modulae<span style="color: #990000">.</span>2mg <span style="color: #993399">828</span> <span style="color: #993399">130</span> intro<span style="color: #990000">.</span>wb raw
|
|
<span style="color: #990000">.</span>/decrunch modulae<span style="color: #990000">.</span>2mg <span style="color: #993399">958</span> <span style="color: #993399">5</span> intro<span style="color: #990000">.</span>song</tt></pre></div></div>
|
|
<div class="paragraph"><p>Now, there should technically be two different music files in Modulae. One
|
|
for the intro, and the other for the main demo. The music player doesn’t
|
|
seem to reference them, so I’m guessing a <strong>second</strong> music player is actually loaded
|
|
at another point. Instead of hunting for it, I decide to check the entries
|
|
of the main loader. Sure enough, I find another song and wavebank.</p></div>
|
|
<div class="listingblock">
|
|
<div class="content"><!-- Generator: GNU source-highlight 3.1.8
|
|
by Lorenzo Bettini
|
|
http://www.lorenzobettini.it
|
|
http://www.gnu.org/software/src-highlite -->
|
|
<pre><tt><span style="color: #990000">.</span>/decrunch modulae<span style="color: #990000">.</span>2mg <span style="color: #993399">189</span> <span style="color: #993399">133</span> demo<span style="color: #990000">.</span>wb raw
|
|
<span style="color: #990000">.</span>/decrunch modulae<span style="color: #990000">.</span>2mg <span style="color: #993399">162</span> <span style="color: #993399">27</span> demo<span style="color: #990000">.</span>song</tt></pre></div></div>
|
|
<div class="paragraph"><p>And thus we have both songs extracted. The final step is to trim off the
|
|
excess padding. Since the songs are padded to block boundaries, they have
|
|
useless extra padding at the end. <code>trimwb</code> and <code>trimmusic</code> will calculate the
|
|
proper length of the wavebank and song files and output trimmed down versions.</p></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
<div id="footnotes"><hr /></div>
|
|
<div id="footer">
|
|
<div id="footer-text">
|
|
Last updated
|
|
2017-08-21 10:48:15 MST
|
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