The following script demos a simple db program. It creates two persons
and two gifts. It creates a variable which is assigned a person. Based
on the gender of the person referred by variable, another variable is
assigned a gift. The variables are things in the db.

// Create gender class and make it an item in main directory.
CREATE *.name=+gender & it.item~in = dir;

// Create persons john and mary.
CREATE *.name=+person & it.item~in = dir;
CREATE *.name=+john & it.cls=person & it.gender=+male;
CREATE *.name=+mary & it.cls=person & it.gender=+female;

// Create toy xbox.
CREATE *.name=+toy & it.item~in = dir;
CREATE *.name=+xbox & it.cls=toy;

// Create perfume Chanel #5.
CREATE *.name=+perfume & it.item~in = dir;
CREATE *.name=+chanel #5 & it.cls=perfume;

// Create variables personX and giftX.
CREATE *.name=+variable & it.item~in = dir;
CREATE *.name=+personX & it.cls=variable;
CREATE *.name=+giftX & it.cls=variable;

// Create verb which allows vars to referTo something.
CREATE *.name=+refersTo & it.cls=verb;
CREATE refersTo.vbType = cr;

// Make var personX referTo john.
CREATE personX.refersTo = john;

// Set giftX based on gender of thing referred by personX.
IF (EQUAL ((personX.refersTo=%).gender=%) male) T(CREATE giftX.refersTo
= xbox) E(CREATE giftX.refersTo = chanel #5);

// Show what giftX refersTo in msgbox.
// Shows xbox.
OUTPUT (giftX.refersTo=%);

// Delete what giftX refersTo.
DELETE giftX.refersTo=xbox;

// Change personX from john to mary.
UPDATE personX.refersTo = () > mary;

// Set giftX based on gender of thing referred by personX.
IF (EQUAL ((personX.refersTo=%).gender=%) male) T(CREATE giftX.refersTo
= xbox) E(CREATE giftX.refersTo = chanel #5);

// Show what giftX refersTo in msgbox.
// Shows Chanel #5.
OUTPUT (giftX.refersTo=%);

// Note: requires XDb2 v5.0.0