Regardless of the source of the libraries and their intended applications, there is a clear need for various metadata associated with the library and its constituent spectra. There have been for many years several different popular spectral library formats in proteomics, including the MSP format used by NIST, the splib format used by SpectraST , the blib format used by Bibliospec, simple yet ad hoc tab-separated formats for DIA applications, and others. Similarly, in metabolomics the MSP format and the Mascot Generic Format (MGF) are commonly used. While these formats are fit for the purpose of storing the spectra themselves, they all lack an adequate and well-documented mechanism for providing rich metadata about the spectra, including their provenance. Several of these formats store limited metadata using ad hoc keywords in a comment field. There are common conventions, but these have evolved over the years with no formal documentation or consensus between tools or domains. As spectral libraries become ever more important for mature and emerging applications, a need for a community standard spectral library format with extensive metadata has been identified. It is recognized that a standardized format for spectral libraries will greatly facilitate the systematic compilation, dissemination, and utilization of spectral libraries in the research community.