And, one question about the future

My question about "the future" is what the plan or goal for making 
xml-apis "match" what ever is in a particular version of JRE's? 

I know in 1.3, they sure didn't, in 1.4, they were close, but not quite, 
and there were differences between IBM's and Sun's (not sure about 
others). 

And ... not sure about 1.5 ... maybe they match exactly? 

So, my question is, is there a real efffort to be sure they match exactly 
for any particular future generation of JRE's, or, 
is it a deliberate plan to allow your selves the flexibility to differ 
from current JRE's, so you can, if desired, get a "head start" , 
so to speak, on new specs? 

Again, any insights welcome.