The manual content and the user notes are separated to php_manual_LANG.chm and php_manual_notes.chm. There were several resons to do this, including:
All these benefits lead us to provide the manual the way you can see it right now. This distribution had the effect on the full text search that you get search results from the manual content and from the user notes as separate ones. The "Location" column shows the source of the result, also enabling you to "add precedence" to manual content results with ordering the results by "Location". User note page titles are also prefixed with "N:" to make them easily distinguishable in the favorites list (there's no location info in the favorites list).