Here is the problem:
The file I want to sort has 3 types of records.
If the first byte has value 0, it means a header record.
If the first byte has value 1, it means a value record.
If the first byte has value 3, it means a trailler record.
I need to sort the file, without taking into account header and trailler records.
However, these records should figure in output file, at the first position and last position respectively.
I'll always have a header and a trailler record, and the number of records is variable.
My key is:
What should I add to the key, to have this behavior?