This policy setting allows you to turn off the ability to use a custom dictionary.
If you enable this policy setting, you cannot add, edit, and delete words in the custom dictionary either with GUI tools or APIs. A word registered in the custom dictionary before enabling this policy setting is not used for conversion.
If you disable or do not configure this policy setting, the custom dictionary can be used by default.
For Japanese Microsoft IME, [Clear auto-tuning information] works, even if this policy setting is enabled, and it clears self-tuned words from the custom dictionary.
This policy setting is applied to Japanese Microsoft IME and Simplified Chinese Microsoft Pinyin.