You are looking at the Index of footnotes, which collects all the footnotes and lists them as endnotes.
Footnote #48 of this article is attached to “the sacraments confer the grace that they signify.”
DS refers to Denzinger, a compilation of Church documents. This shows where the Church taught the idea that was footnoted:
1605 Dz 848 Can. 5. If anyone shall say that these sacraments have been instituted for the nourishing of faith alone: let him be anathema.
1606 Dz 849 Can. 6. If anyone shall say that the sacraments of the New Law do not contain the grace which they signify, or that they do not confer that grace on those who do not place an obstacle in the way, as-though they were only outward signs of grace or justice, received through faith, and certain marks of the Christian profession by which the faithful among men are distinguished from the unbelievers: let him be anathema.
I think @BartholomewB was talking about an index in the print copies that does not appear with the online copy. I am pretty sure he did not mean this index of footnotes.