key

The required name of the tag. The string value can be from 1 to 128 Unicode characters in length and can't be prefixed with "aws:" or "rds:". The string can contain only the set of Unicode letters, digits, white space, '', '.', '/', '=', '+', '-' (Java regex: "^([\\p{L}\\p{Z}\\p{N}.:/=+\\-]*)$").