Hello Grant,
Fot the Gist you can write a one sentence summary of the book. Yeah it could very well be a phrase that captures the author's main point. In case your purpose is only concerned with the subset, then it is always a good idea to restrict your summary to that subset.
For branches specified as "Keypoint Related to Themes" you can write down the key words that susbtantiate or describe the theme. These could be your trigger words. Ideally you will use these words in a discussion to elaborate on the theme. Theme relates to your purpose. Just a gentle reminder, that purpose is supreme in PhotoReading Whole Mind system.
I hope I have been of some help to you.
God Bless You.
Kind regards
Vaibhav Sharma
