Each system must include the State's rigorous definition of developmental delay, consistent with §§ 303.10 and 303.203(c), that will be used by the State in carrying out programs under part C of the Act in order to appropriately identify infants and toddlers with disabilities who are in need of services under part C of the Act. The definition must—

(a) Describe, for each of the areas listed in § 303.21(a)(1), the evaluation and assessment procedures, consistent with § 303.321, that will be used to measure a child's development; and

(b) Specify the level of developmental delay in functioning or other comparable criteria that constitute a developmental delay in one or more of the developmental areas identified in § 303.21(a)(1).