Original Exploration Licence Area at the time it was first Granted

Contains details only on current titles - this layer does not contain every EL at first grant. The idea is to save the original area and when the title finally expires, transfer it to the expired layers eg ELHST本数据集仅涵盖当前有效权属的相关详情——该数据层未收录首次授予时的全部EL。其设计初衷为留存原始数据域，待该权属最终到期后，将其迁移至过期数据层，例如ELHST。