Is the following possible:
{% set issue = craft.entries(section: 'issues', slug: 'october-2014').first() %}
{% set categoryOne = craft.categories({ group: 'articles', slug: 'category-slug-one'}) %}
{% set categoryTwo = craft.categories({ group: 'articles', slug: 'category-slug-two'}) %}
{% set categoryThree = craft.categories({ group: 'articles', slug: 'category-slug-three'}) %}
{% for entry in craft.entries({
section: 'articles',
relatedTo: ['and',
['or',
{ targetElement: categoryOne },
{ targetElement: categoryTwo },
{ targetElement: categoryThree }
],
{ targetElement: issue }
]
}) %}
{{ entry.title }}
{% endfor %}
Attempting to return articles associated with a specific issue from within one of three specific categories.
It appears the parseRelationParam function looks at the first array element to determine the operator but I'm hoping someone has a solution.