685—12.2 (263B) Iowa site records. Specific locational and descriptive information on each reported site is placed on official Iowa Site Record sheets. Blank sheets and a packet of information explaining how they are to be completed are available from OSA upon request.
	 12.2(1) The official site numbers used on site record sheets and in the inventory conform to the trinomial system which incorporates state and county designations coded with sequentially numbered sites within each county.
	 12.2(2) Numbers are usually assigned on an individual basis as needed. In special cases, blocks of site numbers shall be allocated by OSA to researchers to facilitate projects.
	  a.   	 Blocks of site numbers will be issued for periods of time up to one year.
	  b.   	 If an individual or agency fails to utilize assigned numbers within the period allowed, the numbers may be renewed or revoked depending upon the circumstances.