How can I explode text to a text list (many documents)?

Perform a Diff and select a field to change (you can use the Values button to look at the values), then use the Modify button to change (i.e. explode) the item in question.

In the Modify window, click the Use a formula button, to enter formula mode. In this window, enter a formula to explode the field type from a text to a text list. Remember, this formula will be applied to the field item for all documents selected for this Modify operation. Your formula will probably end up looking like this:

@Explode(myfield,",")