A global attribute, featureType, is required for all Discrete Geometry representations except the orthogonal multidimensional array representation, for which it is highly recommended.  The exception is allowed for backwards compatibility, as discussed in 9.3.1.  A Discrete Geometry file may include arbitrary numbers of data variables, but (as of CF v1.6) all of the data variables contained in a single file must be of the single feature type indicated by the global featureType attribute, if it is present.1   The value assigned to the featureType attribute is case-insensitive;  it must be one of the string values listed in the left column of Table 9.1.