U+nnnn
Unicode
characters are commonly referred to using a notation like
U+nnnn
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
U+nnnn
is needed for referring to characters uniquely in contexts where
one cannot reliably present the character itself.