Don't know the meaning of this symbol in equation for LGD.?

I'm attempting to implement a program to plot a TCIF spectrogram, a sort of 3-D Fourier spectrogram, and the paper specifying the technique details two distinct approaches. I've successfully implemented the algorithm using Finite Difference approximations, and would like to implement the Auger-Flandrin method. The problem is, there are two symbols which I am not familiar with, which I suppose amount to

fancy 'R'

and

fancy 'J'

I don't rightly know what the correct term for letter written in this type of font are. Sort of a calligraphy appearance. Fancy seems appropriate enough, but doesn't help me research the meaning of it.

These symbols are not explained in the paper, nor used in any other context.

http://s319.photobucket.com/albums/mm470/femtorgon...

If anyone can at least point me in the right direction, or give me some search term that I might be able to start research with, that would be immensely helpful.