Mostly it strips out ‘math variable names that jerks would use to embolden their spam headlines for emphasis’, which is indeed annoying and results in this:

∂ₓₙ = [(₁ ⊗ ʹ) (₂ ⊗ ʹ) ( ⊗ ₁) ( ⊗ ₂)]

And last I checked, BPL is in the same boat.