Maps DEFINITIONS AUTOMATIC TAGS ::=
BEGIN

XY ::= SEQUENCE { x INTEGER DEFAULT 0, y INTEGER DEFAULT 0 }

xy1 XY ::= { x 42, y 17 }
xy2 XY ::= { }
xy3 XY ::= { y 999 }

S ::= SEQUENCE {
  xy XY DEFAULT { x 100, y 100 },
  os OCTET STRING OPTIONAL
}

s1 S ::= {}

END