 They have the name of the base written inside the tail flash and a five-digit number in which all digits are printed in the same size.In most cases, the first digit represents the last digit of the fiscal year, and the remaining digits identify the four-digit sequence number.In cases where more than 10,000 aircraft were ordered in a single year (1964, for example), the complete 5-digit sequence number - without FY identification - is used.