  The NASA Exoplanet Exploration Program's SAG15 group has solicited,
collected, and organized community input on high-level science questions that
could be addressed with future direct imaging exoplanet missions and the type
and quality of data answering these questions will require. Input was solicited
through a variety of forums and the report draft was shared with the exoplanet
community continuously during the period of the report development (Nov 2015 --
May 2017). The report benefitted from the input of over 50 exoplanet scientists
and from multiple open-forum discussions at exoplanet and astrobiology
meetings. The SAG15 team has identified three group of high-level questions,
those that focus on the properties of planetary systems (Questions A1--A2),
those that focus on the properties of individual planets (Questions B1--B4),
and questions that relate to planetary processes (Questions C1--C4). The
questions in categories A, B, and C require different target samples and often
different observational approaches. For each questions we summarize the current
body of knowledge, the available and future observational approaches that can
directly or indirectly contribute to answering the question, and provide
examples and general considerations for the target sample required.
