句子中的where引导的是什么从句啊?History proceeds by the interpretation of

句子中的where引导的是什么从句啊?History proceeds by the interpretation of evidence:where evidence is a collective name for things which ……
History proceeds by the interpretation of evidence:where evidence is a collective name for things which singly are called documents,and a document is a thing existing here and now,of such a kind that the historian,by thinking about it,can get answers to the questions he asks about past events.
如果where引导的是定语的话，先行词应该是evidence，但是where从句中也出现了这个词，另外，and a document这个是什么成分和谁是并列的，