Described herein are methods for generating concise descriptions of an IC layout. The description from a first format is read and deciphered for determining any patterns in any repetition of elements of an IC layout. The repetitions are then expressed in a concise form to further compress the description. Duplicative information can be avoided by the use of these methods and systems. The repetition patterns described include row-type and column-type patterns. Some selected element instances may be described as part of a random-type arrangement of element instances instead of being described individually.