The accounting procedures set forth in this Subchapter are designed to be as flexible as possible to fit a State-wide program participated in by local agencies, some of which represent extremes in size and organization. Under the circumstances, modifications of or supplements to this Subchapter will be inevitable and will follow from time to time. Until such modification or supplements are issued, however, it is requested that no deviation be made from the mandatory procedures prescribed without the prior written approval of the Division of Housing. With respect to non-mandatory procedures, modifications may be made by the local agency as described in section 1640-1.4, above. Refinements in this Subchapter can come only in the light of the experience gained in the application to the operations of the various local agencies. Comments and suggestions intended to clarify and simplify the material and procedures are solicited from the local agencies and others who have occasion to use or refer to this Subchapter in their work.