Alerts are hierarchical: a single alert can have multiple applicability periods, multiple affected entities, and translations to multiple languages. The read function flattens all of that to a tabular format, with one row for every combination of applicability, entity, and language.
test_data_alert_unwrapping.RdThis has four alerts. The first one has all fields filled out, and has two each of applicability periods, entities informed, and language - so it should become 222 = 8 rows. The second one is identical but is missing some (but not all) Spanish translations The third one does not have Spanish translations, so it should become 2*2 = 4 rows The fourth one has no time ranges, entities, or languages so should just be one row the fifth one is all NA