It is possible to block metadata inheritance by using the @inheritance attribute. When set to true, the children topics inherit the metadata key and its value. When set to false, they do not.
It is also possible to block the inheritance at the document level.
Example
<?xml version="1.0" encoding="UTF-8"?>
<ft:map ...>
...
<ft:toc>
<ft:node ft:originId="192fe" ft:title="Introduction" href="intro/introduction.html" type="topic">
<ft:metas>
<ft:meta key="product">myProduct</ft:meta>
<ft:meta key="audience" inheritance="false">beginner</ft:meta>
</ft:metas>
</ft:node>
...
</ft:toc>
</ft:map>
In this situation, the children topics of Introduction do not inherit the audience metadata key of value beginner. They do inherit the product metadata key of value myProduct.