PlDoc When you need help with PlDoc (SWI-Prolog documentation), e.g. writing declaration headers, creating output, etc. Predicate When you are not sure which SWI-Prolog base or library predicate, combination of predicates, or options for a predicate(s) to use. Data Structure Use this category if you need help with a specific data structure or trying to find a data structure, e.g. Association lists or Ordered Sets Tools Use when needing help with tools such as Emacs as opposed to needing help with coding. Algorithm Use this category when you need help implementing an algorithm. If you need help with a single predicate then use the Help - Predicate category instead. Pack Use this when you need help with a Pack.