Because the administrator might have used different names for roles than you did, the mapping of roles provides an opportunity to bridge the difference in names.
由于管理员创建的角色名可能与您创建的不同，角色映射消除了名称之间的差异。
2
First, the DOM tree model differs subtly from the XPath model needed by an XSLT processor, and this difference imposes run-time costs in mapping one model to the other.