Bearings and bearing systems as follows: a. Ball bearings or solid ball bearings, having tolerances specified by the manufacturer in accordance with ABEC 7, ABEC 7P, or ABEC 7T or ISO Standard Class 4 or better (or equivalents) and having any of the following characteristics. a.1. Manufactured for “use” at operating temperatures above 573 K (300 degrees C) either by using special materials or by special heat treatment; or a.2. With lubricating elements or component modifications that, according to the manufacturer’s specifications, are specially designed to enable the bearings to operate at speeds exceeding 2.3 million DN. b. Solid tapered roller bearings, having tolerances specified by the manufacturer in accordance with ANSI/AFBMA Class 00 (inch) or Class A (metric) or better (or equivalents) and having any of the following characteristics. b.1. With lubricating elements or component modifications that, according to the manufacturer’s specifications, are specially designed to enable the bearings to operate at speeds exceeding 2.3 million DN; or b.2. Manufactured for “use” at operating temperatures below 219 K (54 degrees C) or above 423 K (150 degrees C). c. Gas-lubricated foil bearing manufactured for “use” at operating temperatures of 561 K (288 °C) or higher and a unit load capacity exceeding 1 MPa. d. Active magnetic bearing systems. e. Fabric-lined self-aligning or fabric-lined journal sliding bearings manufactured for “use” at operating temperatures below 219 K(-54 degrees C) or above 423 K (150 degrees C).