INT: An integer,
UINT: An unsigned integer,
FLOAT: A floating point number,
BOOLEAN: A boolean value,
WORD: A string containing A-Z or underscores only (not case sensitive),
ALNUM: A string containing A-Z or 0-9 only (not case sensitive),
CMD: A string containing A-Z, 0-9, underscores, periods or hyphens (not case sensitive),
BASE64: A string containing A-Z, 0-9, forward slashes, plus or equals (not case sensitive),
STRING: A fully decoded and sanitised string (default),
HTML: A sanitised string,
ARRAY: An array,
PATH: A sanitised file path,
USERNAME: Do not use (use an application specific filter),
RAW: The raw string is returned with no filtering,
unknown: An unknown filter will act like STRING. If the input is an array it will return an
array of fully decoded and sanitised strings.