c/o Y. Ogawar, ISAS, 3-1-1 Yoshinodai, Sagamihara, Kanagawa, JAPAN 229

Metric type II bursts (along with EIT waves and chromospheric Moreton waves) reveal the existence of globally expanding large-scale wave disturbances in the low-to-middle corona. This paper discusses Yohkoh soft X-ray observations that reveal the driver of such a wave to be an ejection from an extremely compact source at the beginning of a flare's impulsive phase.