I would take that to mean Appendix A (certain standardized sizes and designs in the 6th Ed), Appendix D (higher-strength design, now the default method in the body of API-650) and Appendix B (foundation design).
Usually, "App" is part of the nameplate text, there's a box, and the "ABC" whatever is stamped in the box, all that apply.
It looks like those Appendices have changed applications some through the years, so the current ones don't correspond to the 6th Edition ones.
And in the current standard, they're "Annexes", but in all the older standards they were "Appendices".