Board Thread:Getting Technical/@comment-3297312-20130331040948/@comment-4674838-20130406173021

Yeah, it looks like they do have mw:Extension:Arrays installed, as you can see with code like #arraydefine and #arrayprint in w:c:jch02140:Template:Item.

You may be able to request the extension to be enabled on your wiki via Special:Contact. Otherwise, without that extension, the template won't work.