You are likely to encounter “+tn_0” in one of at least three places…
In a compiled .42f you may see it as the value of the tabName attribute for a Table node
In the AUI Tree as the value of the tabname attribute of the Table node
In stored settings, you may see +tn_0 as the key value for a tables stored settings
To learn more about why this +tn_0 occurs, read
https://4js.com/ask-reuben/ig-204/