In the past, I've noticed that entries in the symbol table (%::) always have a SCALAR component. I guess every package symbol always has a scalar component due to how Perl's guts are written.

package main;

our %test = ( a => 1 );

print('SCALAR: ', (  *{ $::{'main::'}{'test'} }{SCALAR}  )?1:0, "\n");
print('ARRAY:  ', (  *{ $::{'main::'}{'test'} }{ARRAY }  )?1:0, "\n");
print('HASH:   ', (  *{ $::{'main::'}{'test'} }{HASH  }  )?1:0, "\n");

${  *{ $::{'main::'}{'test'} }{SCALAR}  } = 'scalar';
print("$test\n");

__END__
SCALAR: 1
ARRAY:  0
HASH:   1
scalar
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