In Figure and Figure , we show spectra from different NIST spectral libraries and their equivalent mzSpecLib text rendering, highlighting the mapping between the MSP keyvalue pairs and the controlled vocabulary terms. By cataloging many MSP files from NIST and other sources, we identified synonymous or conditionally equivalent keys. For example, at least eight distinct terms keys were found that corresponded to the analyte precursor m/z, six terms for scan polarity, and eight terms for collision energy (CE). For example, in Figure the HCD key is equivalent to the CE key in Figure .