In a PhD program of study, what does "emphasis on descriptive material" mean? For example, an interdisciplinary PhD program that I am reading about says this about their program:

"The program differs from the regular departmental offerings in science mainly by its interdisciplinary approach and emphasis on mathematics and physics, with less emphasis on descriptive material from any one discipline."

What does descriptive material mean here?
I'm guessing, but the way I read it is 'you're going to have to do proper calculations, not just waffle'. That is, I would take the 'descriptive material' to be in contrast with 'mathematics and physics'.