Reconstructing the original manuscript
The “Hierarchy of propositions and functions” (HPF) consists of 53 leaves, all but one with writing on only one side. The item is in file RA 230.031400. The leaves are all numbered (foliated) with only one exception, from 1 to 78. There are some duplicate numberings and some numbers out of order at the end of the manuscript. Almost all of the 25 missing folios reappear renumbered in the manuscripts for the Introduction and Appendix A. The numbers are written in the upper right of each page, underlined following Russell's practice, and they are reproduced here as italic. There are very few deletions, except for the last few pages. Some entire pages were deleted with a single line, or large ‘X’ through the whole page, and that is indicated where it happens.
At one point this HPF manuscript was the entire draft of the new material for the second edition. Russell then decided to split the new material into an introduction and an appendix. Long sections of the manuscript were moved to become parts of the Introduction to the second edition, and the core of Appendix A. Several folios were added at the beginning of each of those two. The rest of the material in the HPF manuscript was revised to differing extents and turns up in the published version there and in the Introduction, Appendix A, and Appendix B.