I believe this is what you want.......I arbitrarily set the GMT offset to -9 hours.....set it to whatever you need it to be
If(
Contains( :Weightime, "ST" ),
Informat( Substr( :Weightime, 1, Contains( :Weightime, "ST" ) - 2 ), "ddMONyyyy h:m:s" ),
Contains( :Weightime, "GMT" ),
Informat( Substr( :Weightime, 1, Contains( :Weightime, "GMT" ) - 2 ), "ddMONyyyy h:m:s" )
-In Hours( 9 )
)
Jim