A basemap (also called a background map) provides geospatial context for the datasets that you work with. The basemap that the Data Inspector Library uses is derived from the HERE Optimized Map for Visualization (OMV) catalog. And the data for OMV is based on the HERE Map Content Data catalog. This kinship ensures that the basemap is always fresh (weekly updates), accurate, and compatible with other types of data stored on the HERE Open Location Platform (OLP).
The basemap is delivered as vector tiles in the HERE Optimized Map for Visualization (OMV) format. Optimized implies that OMV has been specifically adapted for performant web-based visualizations through simplifying geometries and filtering data. OMV follows the Mapbox Vector Tiles (MVT) specification - an industry standard for map vector tiles.