Rule 4-5-3 about using relational operators to determine uint8_t

[chgros]

Thanks for this, but we'd like an answer to the question: is the code compliant or not? I believe it's not compliant, because 

Code:

uc <= '9'

compares a character expression ('9') to something that's not a character, and that's not among the exceptions. Our customer claims it's compliant because of the exception to check for a digit.