What does “representable” mean in C11?

Question

According to C11 WG14 draft version N1570:

The header declares several functions useful for classifying and mapping cha

Answer 1

The revealing quote (for me) is §6.3.1.3/1:

if the value can be represented by the new type, it is unchanged.

i.e., if the value has to be changed then the value can't be represented by the new type.

Therefore an unsigned type can't represent a negative value.

To answer the question in the title: "representable" refers to "can be represented" from §6.3.1.3 and unrelated to "object representation" from §6.2.6.1.

It seems trivial in retrospect. I might have been confused by the habit of treating b'\xFF', 0xff, 255, -1 as the same byte in Python:

>>> (255).to_bytes(1, 'big')
b'\xff'
>>> int.from_bytes(b'\xFF', 'big')
255
>>> 255 == 0xff
True
>>> (-1).to_bytes(1, 'big', signed=True)
b'\xff'

and the disbelief that it is an undefined behavior to pass a character to a character classification function e.g., isspace(CHAR_MIN).