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Give a name to byte and code point's underlying number
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This would be useful for whatwg/url#518 and also clarifies isomorphic decode/encode a bit.
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annevk committed May 15, 2020
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19 changes: 13 additions & 6 deletions infra.bs
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Expand Up @@ -443,7 +443,10 @@ JavaScript <b>null</b> value. [[!ECMA-262]]
<h3 id=bytes>Bytes</h3>

<p>A <dfn export>byte</dfn> is a sequence of eight bits, represented as a double-digit hexadecimal
number in the range 0x00 to 0xFF, inclusive.
number in the range 0x00 to 0xFF, inclusive. A <a>byte</a>'s <dfn for=byte>value</dfn> is its
underlying number.

<p class=example id=example-byte-value>0x40 is a <a>byte</a> whose <a for=byte>value</a> is 64.

<p>An <dfn export>ASCII byte</dfn> is a <a>byte</a> in the range 0x00 (NUL) to 0x7F (DEL),
inclusive. As illustrated, an <a>ASCII byte</a>, excluding 0x28 and 0x29, may be followed by the
Expand Down Expand Up @@ -535,14 +538,17 @@ contains, in the range 0x61 (a) to 0x7A (z), inclusive, by 0x20.

<p>To <dfn export>isomorphic decode</dfn> a <a>byte sequence</a> <var>input</var>, return a
<a>string</a> whose <a for=string>code point length</a> is equal to <var>input</var>'s
<a for="byte sequence">length</a> and whose <a>code points</a> have the same values as
<var>input</var>'s <a>bytes</a>, in the same order.
<a for="byte sequence">length</a> and whose <a>code points</a> have the same
<a for="code point">values</a> as the <a for=byte>values</a> of <var>input</var>'s <a>bytes</a>, in
the same order.


<h3 id=code-points>Code points</h3>

<p>A <dfn export lt="code point|character">code point</dfn> is a Unicode code point and is
represented as a four-to-six digit hexadecimal number, typically prefixed with "U+".
represented as a four-to-six digit hexadecimal number, in the range U+0000 to U+10FFFF, inclusive.
It is typically prefixed with "U+". A <a>code point</a>'s <dfn for="code point">value</dfn> is its
underlying number.

<p>A <a>code point</a> may be followed by its name, by its rendered form between parentheses when it
is not U+0028 or U+0029, or by both. Documents using the Infra Standard are encouraged to follow
Expand Down Expand Up @@ -759,8 +765,9 @@ ordering will not match any particular alphabet or lexicographic order, particul
<li><p><a>Assert</a>: <var>input</var> contains no <a>code points</a> greater than U+00FF.

<li><p>Return a <a>byte sequence</a> whose <a for="byte sequence">length</a> is equal to
<var>input</var>'s <a for=string>code point length</a> and whose <a>bytes</a> have the same values
as <var>input</var>'s <a>code points</a>, in the same order.
<var>input</var>'s <a for=string>code point length</a> and whose <a>bytes</a> have the same
<a for=byte>values</a> as the <a for="code point">values</a> of <var>input</var>'s
<a>code points</a>, in the same order.
</ol>

<hr>
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