Having read this, and after checking what "BBY" and "ABY" meant, I would be tempted to store the years as a number. Then use a negative number for BBY and a positive for ABY. I would probably leave it at that, but I think you could create a column that displays this as a positive number with the suffix. But, I'm not sure if you could get this column to sort using the original. Unfortunately, I don't have my laptop and Calibre with me today to experiment. Though it is fortunate for my work productivity