The catalog file (below) is a pdf version of the spreadsheet listing each letter and document, along with a brief summary.
The name of the transcribed letter or document file, or image, is shown (file extensions for documents, such as .odt files, show as .html in the HTML set).
Included is the location of the letter or document, based on the current filing system of the Haven-Pugh Letter Collection. For example, "2 11-704" refers to box #2, section 11, box type 704. The collection now resides at Portsmouth Athenaeum, so this may change: but the catalog listing is useful for its descriptive summaries and the file names of the transcribed documents.
Some items that are listed that are not part of the Haven-Pugh Letter Collection but are extremely relevant have a source or origin rather than a location (for example, loc.gov, or internet, or the name of another collection).
The Finding Aid provides a general description of the catalog.