# ICU Folding for Latin Subscript Letters

**URL:** <https://discuss.elastic.co/t/icu-folding-for-latin-subscript-letters/186241>\
**Category:** Elasticsearch\
**Created:** [June 18, 2019, 11:45am UTC](https://discuss.elastic.co/t/icu-folding-for-latin-subscript-letters/186241 "2019-06-18T11:45:31Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![tiwari.piyush7](https://avatars.discourse-cdn.com/v4/letter/t/ccd318/32.png) [@tiwari.piyush7](https://discuss.elastic.co/u/tiwari.piyush7)\
**Post date:** [June 18, 2019, 11:45am UTC](https://discuss.elastic.co/t/icu-folding-for-latin-subscript-letters/186241/1 "2019-06-18T11:45:31Z")

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I have created a custom keyword analyzer which has ICU Folding Token filter. While using this analyzer I noticed that following subscript letters are not supported by ICU Folding:

1. ᵢ [LATIN SUBSCRIPT SMALL LETTER I]
2. ᵣ [LATIN SUBSCRIPT SMALL LETTER R]
3. ᵤ [LATIN SUBSCRIPT SMALL LETTER U]
4. ᵥ [LATIN SUBSCRIPT SMALL LETTER V]

ICU Folding filter return an empty string for these letters. I have installed **analysis-icu** plugin as instructed here:  
[https://www.elastic.co/guide/en/elasticsearch/plugins/6.6/analysis-icu.html](https://www.elastic.co/guide/en/elasticsearch/plugins/6.6/analysis-icu.html)

**Example:**  
POST /\<my\_index\>/\_analyze?pretty  
{ "analyzer": "my\_custom\_analyzer", "text": "Kėdaᵢnių" }

**Response:**  
{"tokens" : [{"token" : " **kedaniu**", "start\_offset" : 0, "end\_offset" : 8, "type" : "word", "position" : 0 }] }

As we can see above we've got a token **kedaniu** which should have been **kedainiu**

Following are the ES plugin directory (elasticsearch-6.6.2\plugins\analysis-icu) files for version information:

- analysis-icu-client-6.6.2.jar
- icu4j-62.1.jar
- LICENSE.txt
- lucene-analyzers-icu-7.6.0.jar
- NOTICE.txt
- plugin-descriptor.properties

Any thoughts/suggestions on this?

Few more letters that are not supported and we get empty string in the response:

1. ‸ [CARET]
2. ＾ [FULLWIDTH CIRCUMFLEX ACCENT]
3. ″ [DOUBLE PRIME]
4. ‶ [REVERSED DOUBLE PRIME]

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [July 16, 2019, 11:45am UTC](https://discuss.elastic.co/t/icu-folding-for-latin-subscript-letters/186241/2 "2019-07-16T11:45:37Z")

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