Re:
Smith, Jerome H. The New Treasury of Scripture Knowledge: The Most Complete Listing of Cross References Available Anywhere- Every Verse, Every Theme, Every Important Word. Nashville TN: Thomas Nelson, 1992.
In general, a character before the reference is a code telling us something about the cross-reference

BUG 1: When the code is a Strong number, any code character before the S and the S are not linked - only the Strong number itself is linked. Thus we lose the information encoded in the characters before the number ... and they are important.

BUG 2 or Annoyance. When the code is figure of speech, the f is inactive and we are left to guess that what we are shown is an extract from Bullinger.

As you provide the mouse over interpretation to help users, I would appreciate consistent help ... not dropping the ball when I really need it.