Which of the following items may be referred to as an experimental item when designated?

An item designated as "X-designated" is specifically referred to as an experimental item. This designation is used to indicate that the item is under evaluation or is part of a developmental phase, meaning it has not yet been fully tested or approved for regular use. The "X" designation often signifies that the item is being tested for performance, safety, or effectiveness, and once it has undergone sufficient assessment and meets the required standards, it may be reclassified.

The other designations do not carry the same connotation of being experimental. An "A-designated" item typically signifies active inventory or operational capability, while "Y-designated" may refer to items that have been approved under specific conditions but are not necessarily in an experimental phase. The "Z-designated" items, usually indicate obsolete or obsolete items. Each designation has its own implications and usage within the context of explosive ordnance and military nomenclature, but the "X" designation is distinctly linked to developmental and experimental contexts.