attribute <->
name: anyName of the attribute. When used as attribute to an object, this may be
any name that is not already the name of an instance variable defined at
the class level for this object. It is advised to use a name that is not
defined as a get- or send-method at the class level. For a sheet any
name is valid, but it is advised not to use a name that conflicts with a
get- or send-method defined at class sheet.
See also sheet->value.