Once upon a time, only uppercase letters were accpeted as extra digits (in base > 10) for both int and float
Then 15r1.2E1 was not 15r1.2e1, the later being = 15r12.E
Then it was considered better to understand hexadecimal numbers with lowercase too...
and alternate-base Float became ambiguous and were never fixed :(
This would deserve a new syntax, I don't know what makes sense, 15r1.2_e1 15r1.2#e1 ...
Changing Smalltalk syntax is among the most difficult decisions, expect outcry ;)
Maybe because it's too easy :)