data-*

<h1>Secret agents</h1>

<ul>
  <li data-id="10784">Jason Walters, 003: Found dead in "A View to a Kill".</li>
  <li data-id="97865">
    Alex Trevelyan, 006: Agent turned terrorist leader; James' nemesis in
    "Goldeneye".
  </li>
  <li data-id="45732">
    James Bond, 007: The main man; shaken but not stirred.
  </li>
</ul>

h1 {
  margin: 0;
}

ul {
  margin: 10px 0 0;
}

li {
  position: relative;
  width: 200px;
  padding-bottom: 10px;
}

li:after {
  content: "Data ID: " attr(data-id);
  position: absolute;
  top: -22px;
  left: 10px;
  background: black;
  color: white;
  padding: 2px;
  border: 1px solid #eee;
  opacity: 0;
  transition: 0.5s opacity;
}

li:hover:after {
  opacity: 1;
}

<img
  class="spaceship cruiserX3"
  src="shipX3.png"
  data-ship-id="324"
  data-weapons="laserI laserII"
  data-shields="72%"
  data-x="414354"
  data-y="85160"
  data-z="31940"
  onclick="spaceships[this.dataset.shipId].blasted()" />