Which entry is considered unacceptable for block 21 of AF Form 560?

Block 21 of AF Form 560 is meant for the entry of the member's status and grade, including their service branch and Military Occupational Specialty (MOS) or equivalent. The designation provided in this block should adhere to the appropriate military ranking format and responsibilities.

The entry for an OSI Agent typically refers to a role within the Office of Special Investigations and is linked to specialized and sensitive duties, which may not reflect the standard grade structure for block 21. In particular, while the military does have an OSI designation, the broader application of ranks such as "E6" does not indicate a typical job title within that context. Thus, an entry that simply states "OSI Agent" does not conform to the usual structured format expected for that block, hence making it unacceptable.

In contrast, the other options such as "GS Captain," "E5 Medic," and "E4 Supply Technician" provide explicit rank, job titles, and connect directly to established roles within the military services. They appropriately reflect the individual's designation and are acceptable under the criteria for block 21.