--- /dev/null
+Cache directory resembles the notes hierarchy. Each file corresponds to
+the note file, keeping at least three lines: versioned magic number,
+inode number and ctime value in seconds. All of that is used to
+determine if note was changed and cache is valid.
+
+All other lines contain the links present in the note.
+
+Any change to the file leads to ctime changing and cache invalidation
+with full parsing of the note.
+
+If note's cache is valid, then also the part of HTML is also kept in
+.html-file nearby. It contains all the data till closing <pre>-tag.
+Links and backlinks are generated every time.