The <> (or {}) operator provides a way of specifying a list of expressions to be used for initializing complex (multi-field) variables such as records or structures.
The <> operator encloses a list of comma-separated expressions; individual expressions are optional, but are also positional with respect to the record or structure fields they are intended to initialize. Commas must therefore be used to maintain field positions if empty expressions are encountered in the list.
The initializer list itself may also be left out entirely for those cases where a variable allocation will use the default initializers provided in the record or structure definition (the <> or {} themselves are still required).