An <index-term> is Either
- Single target point (one place) or
- Start of an index range
- When start of a range
- term requires an @id attribute
- matching <index-term-range-end>
points to start of the range
<sec id="sec10-3-3">
<title>Interstate Compacts<index-term id="idx313">
<term>Interstate compacts</term></index-term></title>
...
<sec id="sec10-3-3-5">
<title>Legal Effect of Interstate Compacts</title>
...
<p>Whenever, by the agreement of the States concerned
and the consent of Congress, an interstate compact
comes into operation, it has the same effect
as ... <index-term-range-end rid="idx313"/>
</sec>
</sec>