while ( /([A-Z][0-9]*)=(\S+)|T\d{3}(\d\d)\d/g ) {
    my( $id, $val, $t_expr, $pos ) = ( $1, $2, $3, pos );

    if ( defined $t_expr ) {
        $var{'R10'} = $t_expr;
        next;
    }

    # restlicher Code...
}