What are the valid types for Elasticsearch's word delimiter filter type table?
I found the answer by digging down into the Lucene documentation, from which Elasticsearch is basically quoting.
The docs for WordDelimiterFilterFactory linked to this file in the Subversion repository. It's heavily quoted by the Elasticsearch docs, but contained this additional snippet:
A customized type mapping for WordDelimiterFilterFactory the allowable types are: LOWER, UPPER, ALPHA, DIGIT, ALPHANUM, SUBWORD_DELIM