Reference:
A glass table is a visualization tool that allows you to monitor the interrelationships and dependencies across your IT and business services. You can add metrics like KPIs, ad hoc searches, and service health scores that update in real time against a background that you design. One of the features of glass tables is service swapping, which enables you to toggle displaying KPI values from more than one service on a single widget. You can use service swapping to compare metrics across different services without creating multiple glass tables or widgets. Reference: Overview of the glass table editor in ITSI, [Configure service swapping on glass tables]