Final answer:
A Hazardous Material (HM&E) and Ordnance APL number consist of 13 digits, divided into segments that provide specific information for identification and tracking in naval inventory systems.
Step-by-step explanation:
The number of digits that make up a Hazardous Material (HM&E) and Ordnance Alteration Parts List (APL) number typically consists of 13 digits. These numbers are used extensively within the United States Navy for identifying system-specific equipment and its related parts and components, particularly for maintenance and logistical purposes.
An APL number is divided into various segments that refer to the Navy Identification Code (NIC), the Category, the Equipment Identification Code (EIC), and a Serial Number. Each segment provides unique information about the item it is associated with, ensuring precise identification and tracking within the naval inventory systems.