lector);
        if (!(elem in selectors.system)) {
            selectors.system[elem] = data.some(entry => entry.system == elem && !entry.hide);
        }
        selector.addEventListener('click', e => toggle(e, elem, selectors.system));

        /// Highlighting summary rows and table columns on hovering over the system selector.
        selector.addEventListener('mouseover', e => {
            [...document.querySelectorAll('.summary-row')].map(row => {
                row.className = row.dataset.system 