## 結果ツリーフラグメントの誤解

2004年12月の指向性メモ で言及されてるのを読んでもう一度仕様書を読み直してみる。

Variables introduce an additional data-type into the expression language. This additional data type is called result tree fragment. A variable may be bound to a result tree fragment instead of one of the four basic XPath data-types (string, number, boolean, node-set). A result tree fragment represents a fragment of the result tree. A result tree fragment is treated equivalently to a node-set that contains just a single root node. However, the operations permitted on a result tree fragment are a subset of those permitted on a node-set. An operation is permitted on a result tree fragment only if that operation would be permitted on a string (the operation on the string may involve first converting the string to a number or boolean). In particular, it is not permitted to use the /, //, and [] operators on result tree fragments. When a permitted operation is performed on a result tree fragment, it is performed exactly as it would be on the equivalent node-set.

そんなこんなで、XSLT1.0 でマトモな変換を書こうとするとかなり冗長なことをせざるを得ない状況が生まれるみたいです。めんどくさー