Is it really possible to use 'STREAM::encoding utf-8' in LTM?

It seems the only event that 'STREAM::encoding utf-8' is valid in is 'STREAM_MATCHED'. If you are searching through a UTF-8 payload, and you can't invoke 'STREAM::encoding utf-8' until you get a match, seems to me you can NEVER get a match... I've been groping around in the dark for days on this. Thanks in advance for helping me see the light.