SIGMET Format

[Mamakim]

Hey Guys and Gals,

Given this Sigmet:

MELBOURNE FIR (YMMM)
WSAU21 AMMC 090923
YMMM SIGMET ME02 VALID 090945/091545 YMMC-
YMMM MELBOURNE FIR SEV TURB FCST WI
S4300 E14900 - S4300 E15400 - S3600 E15400 -
S3600 E14900 -
FL230/340 REMAINING STATIONARY WKN.
STS:REVIEW ME01 090515/090945=


Can someone please explain to me what the following means:

1.) WSAU21 AMMC 090923 - is it 9th July from 7pm LMT to 9am LMT?

2.) YMMM SIGMET ME02 VALID 090945/091545 YMMC-YMMM

3.) STS:REVIEW ME01 090515/090945=


Thanks very much in advance

MK

:)