Final answer:
The obligated service time for enlisted personnel upon receipt of orders to OCS depends on current military regulations, which are not detailed in the provided context. For accurate information, refer to the latest guidelines from the respective military branch.
Step-by-step explanation:
The question on how much obligated service time must enlisted personnel have upon receipt of orders to Officer Candidate School (OCS) does not have a straightforward answer within the provided references. This specific detail about requirements for OCS enrollment typically depends on current military regulations and policies. To find the precise obligation terms, one should refer to the latest guidelines provided by their respective military branch as these can change over time and may vary by country. In general, however, once enlisted personnel receive orders to OCS, they may be required to serve for a certain period post-commissioning, which could extend their total service obligation.