Hello,
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I strongly suggest you review Repeating section as html table
Its easier and more efficient than this.
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I've been searching alot for something simple to convert or decode the xml that is generated from the repeated section into a plain text.
most of the blogs uses UDA and some complex workflows to do that.
but i managed to make a simple workflow and some extra controls on Nintex forms to get the text i needed.
it may not be the optimal solution for most cases, but for me, its just what i need 
as a start, create two list columns type of Multiple lines of text "plain text"
- Create a form using Nintex Forms.
- Create the repeated section you need.
note that all controls inside the repeated section must be "Not connected".
only connect the repeated Section to one of the multiple lines column that you created.
name the controls inside that repeated section.
when publishing the form and creating a new item, you will see the below results in the Repeated Action Column.
now we want to get the required data in plain text without the tags
as a start go to you Nintex form
- Add 4 single line textboxes, sort and configure them as demonstrated in the below images.
adding 4 textboxes and sorting them as the below image
note that all the textboxes are not connected to any control
i sorted them this way because after testing, the list column is filled from top to bottom
first textbox is used to "add new line" and add the field name to it, see the image below.
we added the name of the label so the data is displayed properly when converting it to plain text ( you will see the results at the end )
do the same step for text box 2 and 3
-txtbox2: default value: new line Email / not visible.
-txtbox3: default value: new line Address / not visible.
for textbox 4, make its default value a new line only.
now Nintex form part is complete.
now you have to create a workflow to remove all the tags, its a really simple workflow that i discovered by mistake 
- create a variable type of multiple lines of text, lets name it varContent.
- add "set variable" action to your workflow and configure it as shown in image.
- fill this variable with the field where you saved the repeated section and retrieve it as plain text.
- add "set field value" action to your workflow, set the second list column that we created "plain text" with varContent as shown below.
save and publish your workflow, now you should see the expected results.
**Note
if you wish to add spaces in the default value of the textboxes, like this (Name: John) instead of (Name:John). add the below workflow action. (before set field value action)
fn-Replace(variable," ","")
  means the "space" in html but the & was rendered as &
hope this helps
thanks 
