Mode

What the import is: `dependency` (the default when omitted) or `link`. A dependency is schema and is resolved, fetched and cycle-checked as part of this document's closure. A link is data: the document names resources in the linked package through the import's alias exactly as it would through a dependency, but the package is only dereferenced — on demand by a reader, and one hop out (the target package alone, never its closure) by `kanonak validate`, which reports a link that does not dereference. Links carry no version unless the import is pinned with `=`; `match: *` is the natural form for a link, where for a dependency it is the anti-pattern. Any other value is a parse error.