Sorry Michael, this mails stayed as draft, I've just seen that...
so a bit out of ..."hour"

No, that won't solve the problem. If the declared type of the function is element(), then the otherwise branch (whether explicit or implicit, whether executed or not) must return an element.

(It's not like Java, where you can declare a function to return String, and still return null. If you want to allow a "null" return in XSLT, you need to declare the result as "xs:string?").

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Matthieu Ricaud
IGS-CP
Service Livre numirique