UN FAO - how to fill the "Professional Area" field for work experience history

It might seem obvious, but could use some help! When applying for vacancies on jobs.fao.org, you must specify a "Professional Area" for each Work Experience in your employment history. The field contains a list of dropdown options, though it does seem to allow free-form text if you type it in...

I assume it's best to use the dropdowns to fit keywords for an initial scan of my submission; however, I've struggled to select the best "professional area" category for each of my prior work experiences because: 1) You can only select one area for each entry, and 2) Some dropdown descriptions are topical (e.g. "Environment, Natural Resources, and Climate Change") while others are functional (e.g. "Programme Evaluation and Management" or "Information and Knowledge Services"), so you can't use the field to describe both aspects of your experience. This means that if your past role was doing Programme Development, for example (which is actually not a dropdown option, even though it's a commonly required skill for FAO vacancies!), and the organization or work was focused on issues of the Environment and Climate Change, you can only choose one to represent your experience during that time. Given that most FAO vacancies require minimum lengths of experience in both *functional* areas (e.g. Progamme Development, Logistics, HR, etc.) and relevant *issue* areas (e.g. Fishery and Aquaculture, Emergency Relief, etc.), which "professional area" designation should one prioritize to best represent each past experience?

I've looked for a description of the purpose of this field in FAO's general application instructions but do not see any specific reference to it.

Would appreciate anyone's input, especially from those familiar with FAO's initial application review process and how the system calculates whether or not a candidate meets the minimum experience requirements.