InterRail欧洲居留6个月以上还是已经居住满6个月？

原文如下：

You can travel with InterRail if you have a European passport / idenity card or if you have been staying in one of the countries above for more than 6 months (on the first day of validity of your InterRail Pass).


问题是，我有一年的西班牙学生居留，可是居住时间到圣诞节只有4个月不到。如何理解上面这段话呢？大大快出现八。。。。。。。。。。。