Starting in v20, the {} and [] operators can be used to create object and collection literals, respectively.
For example, instead of using New object and New collection like in the following:

$nestedObj:=New object $coll:=New collection(1; 2; 3) $nestedObj.foo:=$coll $obj:=New object("baz"; 4;"qux"; "wer") $nestedObj.bar:=$obj

The above can simply be written as below:

$nestedObj:={foo: [1; 2; 3]; bar: {baz: 4; qux: "wer"}}

Both ways will create the same nested object:

{
  “foo”: [1,2,3],
  “bar”: {
    “baz”: 4,
    “qux”: "wer"
  }
}

As shown above, object and collection literals can be useful for writing nested JSON objects.
Note that key-value pairs in object literals, and values in collection literals, must be separated by semi-colon (;).
Also note that key names in object literals are not surrounded by quotations ("").