here are the docs, pay special attention to the section named "List constants". Constants are always scalars so you need to provide an array reference as the value. But qw// returns a list and not an array reference. Update: erm nope. Let me check this.

update2 Ah. I see. Your problem is that qw// makes a list of strings, and the string "ABC" is not the same as the value of the constant named "ABC".

If you want to use a constant as an element in a list, don't use qw, use (), and make sure the constant is defined before you use it

use constant ABC  => qw/wet ear rtf/;
use constant HEAD => (ABC,"DEF","GHI");

print $_ for HEAD;
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