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The symbols are just the quotation marks for the delimiter for string list entries used in the list.
no delimiter = "List.OfString.ToString(Rules.EvaluatedRules, "")" = 14224
, (comma) as delimiter = "List.OfString.ToString(Rules.EvaluatedRules, ",")" = 1,4224
Regarding to your picture, you can change the delimiter in the last window (Parameters for Property).
Click on "Delimiter (String)" and enter your delimiter:
Here an example of the output: The first lines without delimiter and the next lines comma separated.
Excellent ! Thank you for your help.