These are the different types of queue, as I understand them:
1) Learning queue: All your memorized elements,
2) Priority queue: Elements from your learning queue (i.e. memorized elements), ordered by priority,
3) Pending queue: Elements that are not memorized, meaning not in the learning queue. Once you reach the end of your learning queue, pending element will be memorized and added to your learning queue,
4) Outstanding queue: Memorized elements whose next repetition date is today or before today's date (i.e. the elements you'll be reviewing today). Depending on your settings, the elements will be sorted in different proportions of items/topics, and randomness in their priority,
These are the different types of queue, as I understand them: 1) Learning queue: All your memorized elements, 2) Priority queue: Elements from your learning queue (i.e. memorized elements), ordered by priority, 3) Pending queue: Elements that are not memorized, meaning not in the learning queue. Once you reach the end of your learning queue, pending element will be memorized and added to your learning queue, 4) Outstanding queue: Memorized elements whose next repetition date is today or before today's date (i.e. the elements you'll be reviewing today). Depending on your settings, the elements will be sorted in different proportions of items/topics, and randomness in their priority,
http://supermemopedia.com/wiki/Priority_queue