\ddagger
The double dagger symbol, often used to denote a footnote or reference that is secondary to the primary footnote marked by a single dagger.
Indicating a special or secondary notation for x.
x^{\ddagger}
Referencing a secondary note related to Table 1.
\text{See Table 1\ddagger}
Listing items with secondary footnotes or annotations.
a\ddagger, b\ddagger, c\ddagger