The convention of using an envelope icon to designate the corresponding author is standard editorial practice in academic publishing and requires no formal citation.
The claim states that an envelope icon next to an author's name indicates the corresponding author. This is a straightforward, universally understood graphical convention in scholarly publishing. Under Step 0, statements that are trivially true by definition or direct everyday observation are categorized as common knowledge requiring no citation. Therefore, the balance verdict is set to COMMON_KNOWLEDGE with empty evidence indices.