The SPACE corpus is a large-scale benchmark for general and aspect opinion summarization. At the time of publication, it is the largest collection of human-written reference opinion summaries, as it contains 1,050 summaries including both general (high-level) and aspect-specific summaries for 6 aspects.
Its annotation was a multi-stage effort involving expert native English-speaking annotators. You can access the exact instructions given to the annotators in the links below: