A unique ten-digit identifier for the item/context comprising a concatenation of the Survey Unit number, the Sub-Unit number, and the Item Number. The first four digits correspond to a unit number ranging from 0001 (for Discovery Unit 1) to 9233 (for LOCA 9233). The next string of three digits corresponds to a sub-unit number in the case of experimental units or gridded LOCAs; the string is 000 in the majority of cases where no sub-units were used. The final string of three digits refers to the item-number. As one example, the unique Object-ID number 4005001908 refers to Experimental Unit number 4005, sub-unit 1, and item-number 908 (which in this case corresponded to 15 Medium Coarse Ware body sherds dating to the broad Ancient Historic period).