t chronology = preset.chronology

// UI state
const margin = { left: 0, top: 40, right: 0, bottom: 40 }
let popup = null
let width = 0; let height = 0
let chronologyScale = {}; let svg = {}; let g = {}; let link = {}; let node = {}; let linkLabelPath = {}; let linkLabel = {}
let hoverTimeout = null
let simulation = {}
let zoom = {}
let zoomID = null // node ID to which is programmatically zoomed

// Graph database

let nodes = []; let links = []

parseURLdatabse()
reloadDatabase().then(main)

function reloa