→Stacked images: s/date/data/, some rewording
When you do [[incremental dumps]] there appear the <code>parent</code> symlink and images with pages become dependant on each other.
There appears the 3rd field in the pagemap, called <code>in_parent</code>. When set this boolean value means, that the respective data for the pagemap should be found in the parent images. While searching for data in parent the same algorithm is used -- first the pagemap is resolved, then the data is found in pages. For parent images the
date ( all, or part of it) can also be found in ''its'' parent images.
Respectively, the bottom image (with no parent link) should have no in_parent bits at all.