I know this has been marked as solved...but, I just thought the solution could be simpler than I was making it.

Consequently, I came up with these formulas:

Left digits:
B1: =LEFT(A1,MATCH(1,--ISERR(-MID(A1,{1,2,3,4,5,6,7,8,9},1)),0)-1)

Right digits:
D1: =RIGHT(A1,MATCH(1,--ISERR(-RIGHT(A1,{1,2,3,4,5,6,7,8,9})),0)-1)

Middle letters:
C1: =MID(LEFT(A1,LEN(A1)-LEN(D1)),LEN(B1)+1,10)
There might be shorter solutions, but I suspect they might be too arcane to readily understand.