This format was used by the Programming Data Facility **PDF** application
produced by the **UK Atomic Energy Authority**.
Below is a an example of a **PDF** format structure file :-

0 04-Dec-01 PDF V2.10 FIBONACCI 1, 7, 7, 1 0 Fibonacci SEQ NORM 0 - Initialis e SEQ NORM 0 1 LEAF NORM 2 Calculate SEQ NORM 0 2 LEAF NORM 1 DETAILS-3 ITER NORM 0 - Iteration _1 SEQ NORM -2 i < 32 0 3, 5 LEAF NORM 4 Display SEQ NORM 0 4 LEAF NORM 1 DETAILS-5 ITER NORM 0 - Iteration _2 SEQ NORM -2 i < 32 0 6, 5 LEAF NORM -1 Fibonacci SEQ NORM int fib[32]; int i; 1 fib[0] = 0; fib[1] = 1; 2 i = 2; 3 fib[i] = fib[i-1] + fib[i-2]; 4 i = 0; 5 i++; 6 // Print each number and its Fibonacci product printf("%3d %6d\n", i, fib[i]);