        whose elements represent the various levels of discomfort
            that may be felt by a perceptual agent. Typically, the agent
            must be a living entity. Typically, the sensation is an
            internal feeling, and is more of a long-lasting dull ache
            than a sharp pain (see: #$LevelOfPain).<br />
            <b>guid: </b>3e4ec8be-74ae-11d6-8000-00a0c99cc5ae<br />
            <b>direct instance of: </b>#$CollectionType  <br />
            <b>direct specialization of: </b>