白勇《语法全解》上的一道题：

Originally developed for detecting air pollutants, a technique called proton-induced x-ray emission, which can quickly annalyze the chemical elements in almost any substance without destroying it, is finding uses in medicine, archaeology, and criminology.(正确答案)

白大侠解释说：名词＋called 的结构，修饰关系紧密，可以看作一个整体，所以which定语从句能够跳跃修饰名词techenigue.

疑惑啊，什么叫修饰关系紧密呢？请NN帮忙解释一下。