the implicit key is the host's IP address rather than its name (see section
&<<SECThoslispatsikey>>&).
.next
+.new
+.cindex lookup json
+.cindex json "lookup type"
+.cindex JSON expansions
+&(json)&: The given file is a text file with a JSON structure.
+An element of the structure is extracted, defined by the search key.
+The key is a list of subelement selectors
+(colon-separated by default but changeable in the usual way)
+which are applied in turn to select smaller and smaller portions
+of the JSON structure.
+If a selector is numeric, it must apply to a JSON array; the (zero-based)
+nunbered array element is selected.
+Otherwise it must apply to a JSON object; the named element is selected.
+The final resulting element can be a simple JSON type or a JSON object
+or array; for the latter two a string-representation os the JSON
+is returned.
+For elements of type string, the returned value is de-quoted.
+.wen
+.next
.cindex "linear search"
.cindex "lookup" "lsearch"
.cindex "lsearch lookup type"
The braces, commas and colons, and the quoting of the member name are required;
the spaces are optional.
Matching of the key against the member names is done case-sensitively.
+If a returned value is a JSON string, it retains its leading and
+trailing quotes.
. XXX should be a UTF-8 compare
The results of matching are handled as above.
Field selection and result handling is as above;
there is no choice of field separator.
+If a returned value is a JSON string, it retains its leading and
+trailing quotes.
.vitem &*${filter{*&<&'string'&>&*}{*&<&'condition'&>&*}}*&