A single-value field that contains an enumerated type value, stored as an integer. Nodes that use this field class define mnemonic names for the values. These names should be used when setting or testing
the values of the field, even though the values are treated as integers in the methods.
SoSFEnums are written to file as a mnemonic enumerated type name. The name differs among uses of this field in various node
or engine classes. See the man pages for specific nodes or engines for the names (e.g.
SoDrawStyle).