Hm, you can use a user defined variable to count how much iterations have been done so far.
See Mp3tag Export Scripting Language functions: $put, $puts, $get.
Set variable in display mode (will be printed) ...
$put(MyCounter,$add($get(MyCounter),1))
... counts from $loop starting with 1 by 1 until $loopend.
Set variable in silent mode (will be not printed) ...
$puts(MyCounter,$add($get(MyCounter),1))
... counts from $loop starting with 1 by 1 until $loopend.
Use content of variable ...
$ifgreater($get(MyCounter),20,'do nothing','do something')
But do not expect that the Mp3tag Export Scripting Language do behave like other programming languages!
Here is a test script to visualize the visibility of user defined variables within an export script.
Note the quirky behaviour, when loops are embedded.
20120607.Test.Visibility._put._get.zip (689 Bytes)
DD.20120607.1438.CEST
20120607.Test.Visibility._put._get.zip (689 Bytes)