<li><p>The <a href=#document-base-url>document base URL</a> is the result of the
previous step if it was successful; otherwise it is <a href="#the-document's-address">the
document's address</a>.</li>
previous step if it was successful; otherwise it is <var title="">fallback base url</var>.</li>
</ol></li>
data mining tools are likely to never instantiate browsing
contexts.</p>
<p>A <a href=#browsing-context>browsing context</a> can have a <dfn id=creator-browsing-context>creator browsing
context</dfn>, the <a href=#browsing-context>browsing context</a> that was
responsible for its creation. Unless otherwise specified, a
<a href=#browsing-context>browsing context</a> has no <a href=#creator-browsing-context>creator browsing
context</a>.</p>
<p>If a <a href=#browsing-context>browsing context</a> <var title="">A</var> has a
<a href=#creator-browsing-context>creator browsing context</a>, then the
<code>Document</code> that was the <a href=#active-document>active document</a> of
that <a href=#creator-browsing-context>creator browsing context</a> at the time <var title="">A</var> was created is the <dfn id=creator-document>creator
<code>Document</code></dfn>.</p>
<p>The main <a href=#view>view</a> through which a user primarily
interacts with a user agent is the <dfn id=default-view>default view</dfn>.</p>
<p id=about-blank-origin>The <a href=#origin-0>origin</a> of the
<code><a href=#about:blank>about:blank</a></code> <code>Document</code> is set when the
<code>Document</code> is created, in a manner dependent on whether
the <a href=#browsing-context>browsing context</a> created is a <a href=#nested-browsing-context>nested browsing
context</a>, as follows:
<code>Document</code> is created. If the new <a href=#browsing-context>browsing
context</a> has a <a href=#creator-browsing-context>creator browsing context</a>, then the
<a href=#origin-0>origin</a> of the <code><a href=#about:blank>about:blank</a></code>
<code>Document</code> is the <a href=#origin-0>origin</a> of the
<a href=#creator-document>creator <code>Document</code></a>. Otherwise, the
<a href=#origin-0>origin</a> of the <code><a href=#about:blank>about:blank</a></code>
<code>Document</code> is a globally unique identifier assigned when
the new <a href=#browsing-context>browsing context</a> is created.</p>
<dl class=switch><dt>If the new <a href=#browsing-context>browsing context</a> is a <a href=#nested-browsing-context>nested
browsing context</a></dt>
<dd>The <a href=#origin-0>origin</a> of the <code><a href=#about:blank>about:blank</a></code>
<code>Document</code> is the <a href=#origin-0>origin</a> of the
<a href=#active-document>active document</a> of the new <a href=#browsing-context>browsing
context</a>'s <a href=#parent-browsing-context>parent browsing context</a> at the time
of its creation.</dd>
<dt>If the new <a href=#browsing-context>browsing context</a> is an <a href=#auxiliary-browsing-context>auxiliary
browsing context</a></dt>
<dd>The <a href=#origin-0>origin</a> of the <code><a href=#about:blank>about:blank</a></code>
<code>Document</code> is the <a href=#origin-0>origin</a> of the
<a href=#active-document>active document</a> of the new <a href=#browsing-context>browsing
context</a>'s <a href=#opener-browsing-context>opener browsing context</a> at the time
of the new browsing context's creation.</dd>
<dt>Otherwise</dt>
<dd>The <a href=#origin-0>origin</a> of the <code><a href=#about:blank>about:blank</a></code>
<code>Document</code> is a globally unique identifier assigned when
the new <a href=#browsing-context>browsing context</a> is created.</dd>
<p>Let <var title="">address</var> be the <a href="#the-document's-address" title="the
document's address">address</a> of the <a href=#active-document>active
document</a> of the <a href=#browsing-context>browsing context</a> being
navigated.</p>
<p>If <var title="">address</var> is <code><a href=#about:blank>about:blank</a></code>,
and the <a href=#browsing-context>browsing context</a> being navigated has a
<a href=#creator-browsing-context>creator browsing context</a>, then let <var title="">address</var> be the <a href="#the-document's-address" title="the document's
address">address</a> of the <a href=#creator-document>creator
<code>Document</code></a> instead.</p>
<p><a href=#create-a-script-from-a-node title="create a script from a node">Create a
script</a> from the <code>Document</code> node of the
<a href=#active-document>active document</a>, using the aforementioned script
<p>When it comes time to <a href="#set-the-document's-address">set the document's address</a>
in the <a href=#navigate title=navigate>navigation algorithm</a>, use
the <a href="#script's-base-url">script's base URL</a> as the <a href=#override-url>override
<var title="">address</var> as the <a href=#override-url>override