ATA specification 100 publication contents are organized on four levels; The Unit / Subject numbers are not Preassigned; these numbers and their sequence may be selected by who?

ATA specification 100 publication contents are organized on four levels; The Unit / Subject numbers are not Preassigned; these numbers and their sequence may be selected by who?

• A. Publisher
• B. Government
• C. Manufacturer
• D. Customer

Answer: (C)

In ATA 100 publications, the four-level structure is designed to reflect how the aircraft’s hardware is actually arranged. The Unit or Subject numbers are not fixed by the standard itself; the manufacturer assigns them and decides the sequence to match the way the system is built and how maintenance tasks are performed. This allows the publication to mirror the OEM’s exact architecture and workflow, making it easier for technicians to locate procedures and reference the correct components on a given aircraft. The numbering isn’t standardized across all publications by the ATA or by government bodies, nor is it determined by the customer; it’s determined by the manufacturer.

In ATA 100 publications, the four-level structure is designed to reflect how the aircraft’s hardware is actually arranged. The Unit or Subject numbers are not fixed by the standard itself; the manufacturer assigns them and decides the sequence to match the way the system is built and how maintenance tasks are performed. This allows the publication to mirror the OEM’s exact architecture and workflow, making it easier for technicians to locate procedures and reference the correct components on a given aircraft. The numbering isn’t standardized across all publications by the ATA or by government bodies, nor is it determined by the customer; it’s determined by the manufacturer.