An XML element in a well-formed document may not have two attributes of the same name. Therefore, cardinality operators are not required when attributes are declared.
The declaration of attributes takes the following general form:
<!ATTLIST attributeName attributeType defaultDeclaration >
The attributeType is any of the values in the following list:
CDATA— Any legal XML string.
ENTITY— Value that must match the name of an external unparsed entity.
ENTITIES— An ENTITY, except that more than one whitespace-separated name may occur.
ID— Value that must begin with a letter and then must consist of letters, numeric characters, hyphens, underscores, and period characters. At most, one attribute on any element can be ...