The Collector's Note
This document is a map provided by the Collector as part of the Collector's Diary quest. It is obtained in The Holm Oak Thicket. By itself, the map means nothing. It also cannot be used over the course of general gameplay. It contains a number of locations indicated by marker symbols. The diary is located at one of these symbols. The collector indicates that "two lines" are on the map which would make sense only to him. This is somewhat misleading, as the "two lines" refer to the text in the lower left corner of the map and not literal lines drawn on that map.
In order to decipher the map, Daphne should visit the symbol cave. This trip is not necessary, but it may be useful in helping the player decipher the riddle (and save a lot of crafting mats on shovels).