In TeXForm#
TeXForm parses this entry as a character leaf mapped to U+2206 (INCREMENT).
\bbalpha\bbbeta\bbchi\bbdelta\bbDelta\bbdotlessi\bbdotlessj\bbepsilon\bbeta\bbgamma\bbGamma\bfbbDelta
\bfbbDeltaSymbol
The ∆ symbol (Increment, U+2206), written as \bfbbDelta in LaTeX math mode.