+/* User-missing values.
+
+ struct missing_values is an opaque type that represents a set
+ of user-missing values associated with a variable. Valid sets
+ of missing values depend on variable width:
+
+ - Numeric variables may have up to 3 discrete numeric
+ user-missing values, or a range of numeric values, or a
+ range plus one discrete value.
+
+ - String variables may have up to 3 discrete string
+ user-missing values. (However, for long string
+ variables all bytes after the first MV_MAX_STRING must
+ be spaces.)
+*/
+
+#ifndef DATA_MISSING_VALUES_H
+#define DATA_MISSING_VALUES_H 1