To type a symbol containing lower case characters you can enclose the
symbol in vertical bars, as in
|AbC| or you can put a ``backslash''
before each lower case character you wish to preserve, as in
A\bC are two different ways of writing the same
symbol (just like 2/4 and 1/2 are two different ways of writing the
same rational). The symbol has three characters in its name, the
middle one of which is a lower case b.