[[analysis-asciifolding-tokenfilter]]
=== ASCII Folding Token Filter

A token filter of type `asciifolding` that converts alphabetic, numeric,
and symbolic Unicode characters which are not in the first 127 ASCII
characters (the "Basic Latin" Unicode block) into their ASCII
equivalents, if one exists.  Example:

[source,js]
--------------------------------------------------
"index" : {
    "analysis" : {
        "analyzer" : {
            "default" : {
                "tokenizer" : "standard",
                "filter" : ["standard", "asciifolding"]
            }
        }
    }
}
--------------------------------------------------

Accepts `preserve_original` setting which defaults to false but if true
will keep the original token as well as emit the folded token.  For
example:

[source,js]
--------------------------------------------------
"index" : {
    "analysis" : {
        "analyzer" : {
            "default" : {
                "tokenizer" : "standard",
                "filter" : ["standard", "my_ascii_folding"]
            }
        },
        "filter" : {
            "my_ascii_folding" : {
                "type" : "asciifolding",
                "preserve_original" : true
            }
        }
    }
}
--------------------------------------------------
