+typedef /*@numabstract@*/ int usymId;
+
+extern usymId usymId_fromInt (int p_i) /*@*/ ;
+# define usymId_fromInt(i) ((usymId)(i))
+
+extern int usymId_toInt (usymId p_i) /*@*/ ;
+# define usymId_toInt(i) ((int)(i))
+
+extern bool usymId_isInvalid (usymId p_u) /*@*/ ;
+# define usymId_isInvalid(u) ((u) == usymId_invalid)
+
+extern bool usymId_isValid (usymId p_u) /*@*/ ;
+# define usymId_isValid(u) ((u) != usymId_invalid)