when ever we exicute the script if we got 3 end values out 
those values we took, Average then those end values r calld 
baseline values.

there are some documents in performace testing such as 

test plan
task distribution document
task profiler document 

i known these documents only

For Performance Testing, baseline doc is meant to be the 
criteria that is needed to be achieved by the test,

To be precise, let us consider a scenario that needs to 
executed for 5000users for 2 hours.

We execute a test for 80%load with 4000 users, just to test 
the stability of the application.

Here once we execute the 80% load test, we compare the 
results with the 100% load test that is 5000 users, and by 
this time 5000 users test results will be the baseline 
test. 

Note that 100% test needs to be done before any other 
tests, to compare the results.

Basline mean run the script with minimum load and meaure 
the performance and take that result as the base line for 
your workload

Baseline Docs means simply entry criteria to testing.For
Performance testing P.Test plan,Click stream docs are entry
criteria.

The base line doc for conducting the performance testing is 
Apporch doc or survy doc, based on this apporch doc we can 
prepare perfomance test plan doc and senario design doc and 
call flow doc.........