This document describes VTF3-1.37 for writing and reading traditional Vampir trace files. VTF3 is part of newer Vampir versions and manages the lowest level of the prime source channel there. Developed in 2001, it can be used separately and freely. Except for some records, being part of a research project, all the C-interfaces are defined to be frozen. In addition to pure interface descriptions, the document provides semantic background and gives a lot of hints so that, for example, converter developers get the information they need to imagine what Vampir expects as input. Besides their visualization, VTF3-style all-in-one trace files are more and more often used to comfortably store, process and interchange general temporal states and functions, with or without a high degree of parallelism.