A comma-separated array of individual career fields.
Must be one or more of abilities, age, annual-earnings, annual-openings, categories, core-tasks, description, education-attainment-levels, employment, employment-current, hourly-earnings, humanized-title, knowledge, lay-titles, median-earnings, mocs, national-lq, onet-id, pathways, percent-female, percent-male, plural-short-title, short-title, similar-occs, singular-title, skills, soc-id, soc-title, title, title-slug, typical-ed-level.