When I type on my iPhone running iOS 11 I get these characters as suggestions:
ℬ ℱ ℳ ℛ ℰ
They come only for the letters "B F M R E”. They only appear for single letters and disappear as soon as a second letter is typed.
I have two keyboards active: German and English. I don’t have the smiley keyboard activated.
What are these characters? Are these letters for mathematical equiations? Is this a special font? Are more characters available? Why are they suggested?