If the combination of IO-Link Error Code and Additional Code is listed in the IO-Link Specification, the sever shall use the text of Table C.1 or Table C.2 in column "Incident" as localizedText. Default locale is "en". Servers may provide vendor-specific translations to other languages. (In this case they have to adjust the value of locale as well.)
If the combination of IO-Link Error Code and Additional Code is vendor-specific (0x8101 to 0x81FF) no string shall be provided at all. This is indicated by giving stringTable index -1 as localizedText.
The content of additionalInfo is vendor-specific, but usually an empty string.