targetvalue is calculated as the result of a complex expression or simple expression, it cannot be manipulated within the code of the expression you have created. So you would not be able to use targetvalue.split for example. You can use code on other attributes, and also use code on the sourcevalue, like for example source.split.

So whilst you can create logic to skip using the targetvalue, you cannot manipulate it, the targetvalue is the end result of your logic.

So you could say

if x = y then use “a”, else use “targetvalue”.

Then the result will be either "a" or “targetvalue” from earlier in the logic.