Path Fields
In a path field, the included and excluded elements are constrained to the sub-tree identified by the path. For example, if the path for the field is /A/B/C, only elements in node C, such as A/B/C/D, A/B/C/D/E and /A/B/C/Z, are included or excluded from the field.
A path field may include one or more paths. Multiple paths are treated as the union of the paths. Consequently, each of them will identify a root of a field-instance in a given document.
If a path includes namespace prefixes on some elements, the namespaces must be defined in the same manner used for path range indexes, as described in Defining Namespace Prefixes Used in Path Range Indexes and Fields.
If a path for a field ends in a single node or an attribute, the include/exclude definitions are meaningless.
Each path is given a weight, which is used to boost or lower the relevance of text that is contributed by the path.