The dicts collection

The dicts sub-collection within the system collection of the Content Repository contains the spelling dictionaries for topics and maps.

English and French dictionaries are installed by default. These are standard open-source Hunspell-based spelling dictionaries. They are not developed or maintained by MadCap Software. If you want to add an additional language spellchecker, you can download it at OpenOffice.org

The downloaded files have an .oxt extension. Change this extension to .zip and unzip the package to find a .aff file and a .dic file. Rename these files using the same ISO language codes that you use within your DITA content, those set up in the languages.xml configuration file, and add them to the dicts collection.
Note: The customs sub-collection exists only if you have added words to the spelling dictionaries, which creates custom dictionaries that supplement the default ones.