elevated st segment

there was another question about what test would not help if you suspected a MI, i think the answer is elevated bp because your bp would lower in an mi, (its kinda fun using all these abreviations) anyway, one that would help was an elevated st segment, which confuses me. the st is the rest period, so if it was elevated would it mean that the heart is not resting as much, resting more, or that the rest period lasts longer? the wording just confuses me a bit.