characters are commonly referred to using a notation like
where nnnn is a four-digit hexadecimal (base 16) number specifying the code position of the character in Unicode. For example, the space character has the same code number in Unicode as in ISO 8859-1, namely 32 decimal, 20 hexadecimal; thus, it can be denoted as
U+0020. Generally, a notation like
is needed for referring to characters uniquely in contexts where
one cannot reliably present the character itself.