BC546, BC547, BC548, BC549, BC550 are NPN epitaxial silicon transistors that feature: switching and amplifier; high voltage: BC547, VCEO=65V; low noise: BC549, BC550; they are completement to BC556, BC557, BC558, BC559 and BC560.
The PDF manual contains their features, ordering information, absolute maximum ratings, electrical characteristics, hFE classification, typical performance characteristics and physical dimensions.