========================
Expression: id('chapter1')
Object is a Node Set :
Set contains 1 nodes:
1  ELEMENT chapter
    ATTRIBUTE id
      TEXT
        content=chapter1

========================
Expression: id('chapter3')
Object is a Node Set :
Set contains 1 nodes:
1  ELEMENT chapter
    ATTRIBUTE id
      TEXT
        content=chapter3

========================
Expression: id('chapter1')/p
Object is a Node Set :
Set contains 4 nodes:
1  ELEMENT p
2  ELEMENT p
3  ELEMENT p
4  ELEMENT p

========================
Expression: id('chapter1')//p
Object is a Node Set :
Set contains 4 nodes:
1  ELEMENT p
2  ELEMENT p
3  ELEMENT p
4  ELEMENT p

========================
Expression: id('chapter1')/p[1]
Object is a Node Set :
Set contains 1 nodes:
1  ELEMENT p