Many Level 2 operators expect a dictionary operand that contains key-value pairs specifying parameters to the operator. Language features controlled in this way include halftones, images, forms, patterns, and device setup. This organization allows for optional parameters and future extensibility. For convenience in using such operators, the PostScript language syntax includes new tokens,
<< and >>,to construct a dictionary containing the bracketed key-value pairs. Benefits: Convenience, extensibility.