-When a single-key lookup file is opened, the handle returned by the xxx_open()
-function is saved, along with the file name and lookup type, in a tree. The
-xxx_close() function is not called when the first lookup is completed. If there
-are subsequent lookups of the same type that quote the same file name,
-xxx_open() isn't called; instead the cached handle is re-used.
+ lookup_absfilequery
+
+This is a query-style lookup that must start with an absolute file name. For
+example, the sqlite lookup is of this type.
+
+When a single-key or absfilequery lookup file is opened, the handle returned by
+the xxx_open() function is saved, along with the file name and lookup type, in
+a tree. The xxx_close() function is not called when the first lookup is
+completed. If there are subsequent lookups of the same type that quote the same
+file name, xxx_open() isn't called; instead the cached handle is re-used.