tb2 = copyTB(tb1, 0, 2)
no. of lines in tb1 = 10
tb1 = 
line 01
line 02
line 03
line 04
line 05
line 06
line 07
line 08
line 09
line 10

Compare tb1 with original string: 0
no. of lines in tb2 = 3
tb2 = 
line 01
line 02
line 03