[1] choose - MDC (2010-01-21 13:29:14 +09:00 版) https://developer.mozilla.org/en/XPath/Functions/choose

[2] XProc 2.0: An XML Pipeline Language (2016-07-21 14:35:49 +09:00) https://www.w3.org/TR/2016/NOTE-xproc20-20160721/#p.choose