'' 类型和联合(无限嵌套):
type OtherUDT
x as integer
y as integer
end type
type MyType
a as short
b as integer
c as long
d as OtherUDT
union
e as double
f as single
g as OtherUDT
end union
h as byte
end type
union MyUnion
a as integer
b as longint
c as double
my as MyType
end union