predicate using xml in sql server 2005

Hi ,
I have a doubt using xml in sql sever 2005.
I found in many places while specifying Xpath ,the predicate contains '1'
like
/Inst:root/Inst:Location[1]/Inst:step .
I tried with some other numbers in predicate like
/Inst:root/Inst:Location[2]/Inst:step .i got null value.
Can u plz explain me what is it doing.
thx.
priya.The square brackets are an abbreviation of the position() XPath function.
E.g.:
/Inst:root/Inst:Location[1]/Inst:step
equals to
/Inst:root/Inst:Location[position() = 1]/Inst:step
Return the Inst:step child-node of the first Inst:Location node in the
Inst:root node. A null value for /Inst:root/Inst:Location[2]/Inst:step means
that there is either only one Inst:Location node or there is no Inst:step
node on the second Inst:Location.
ML
http://milambda.blogspot.com/