Dependencies (and Dependency Groups) constraint checking only kicks in when one of the dependent fields is present. It then requires that the other dependent fields are also present.

My problem is just the opposite: determining that at least one of the fields is filled. In other words:

# Should be valid
my %param = ( zip => '55555', postal => '',);
# or
my %param = ( zip => '', postal => '11111',);

# Should not be valid
my %param = ( zip => '', postal => '',);
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If I make both params required, then they're both always required, which is not what I want.

If I make them optional, and add constraints to check that at least one has a value, the constraints are never checked, since the fields are empty.

If I create dependencies, and add constraints to check that at least one has a value, the constraints are never checked, since none of the dependent fields exist.

Thanks anyway for your help, and if you know of a way to do this that I've overlooked, please post.