c – 通过示例的对象和值表示之间的差异

The object representation of an object of type T is the sequence of N
unsigned char objects taken up by the object of type T,where N equals
sizeof(T). The value representation of an object is the set of bits
that hold the value of type T. For trivially copyable types,the value
representation is a set of bits in the object representation that
determines a value,which is one discrete element of an
implementation-defined set of values

N3797 :: 3.9.1 [basic.fundamental]说：

For narrow character types,all bits of the object representation
participate in the value representation.

考虑以下结构：

struct A
{
    char a;
    int b;
}

我认为对于A,并非所有对象表示的位都参与值表示,因为实现添加了填充.但其他基本类型呢？
标准说：
N3797 :: 3.9.1 [basic.fundamental]

For narrow character types,all bits of the object representation
participate in the value representation.
These requirements do not hold for other types.

我无法想象为什么它不能说int或long.什么原因？你能澄清一下吗？