At the moment, when performing a negative keyword search in a specific field, only those nodes that have the field are searched.

In other words: If node type A has the field Software, and node type B doesn't, and am I searching for nodes without the word 'drupal' in Software, all nodes of type B are excluded from the results, even though they for sure do not have the word 'drupal' in Software, since nodes of type B don't have that field.

Is that the behavior one would expect?