push @trace_rw, [ substr($_,0,10), substr($_,0,18) ];

...
$trace_rw[0][0];
$trace_rw[0][1];
...

use constant TRACE_CUR => 0;
use constant TRACE_ORIG => 1;
$trace_rw[0][TRACE_CUR];
$trace_rw[0][TRACE_ORIG];