The key name of the tag. You can specify a value that is 1 to 128 Unicode characters in length and cannot be prefixed with aws:. You can use any of the following characters: the set of Unicode letters, digits, whitespace, _, ., /, =, +, and -.
_
.
/
=
+
-
The value for the tag. You can specify a value that is 0 to 256 characters in length.