California Code, Streets and Highways Code - SHC § 22568

The plans and specifications shall show and describe existing and proposed improvements. The plans and specifications need not be detailed, but shall be sufficient if they show or describe the general nature, location, and extent of the improvements. If the assessment district is divided into zones, the plans and specifications shall indicate the class and type of improvements to be provided for each such zone. The plans or specifications may be prepared as separate instruments or either or both may be incorporated in the diagram as a combined instrument.