Several posts use symbols, such as asterisks, without explaining what they are supposed to mean. Because of this, users may not know what they mean, particularly if they are not linguists.
Such symbols are not particularly useful unless they are listed in List of common symbols and abbreviations or the OP explains why they were used. Otherwise, since I cannot read the OP's mind, I have absolutely no idea what they are for, especially when the symbols used normally mean something else.
Therefore, I think it would be reasonable to expect users to either include an explanation of any symbols not found in List of common symbols and abbreviations in footnotes at the end of the post, or to refrain from using them in favor of parenthetical explanations.
Footnotes need not be used for standard symbols, which should be listed in List of common symbols and abbreviations, but footnotes should be used for other symbols. Additional symbols may be added to that list by anyone who can edit CW posts.