Wildcard usage in index pattern

We can use a wildcard (*) in index name if we want to search multiple indexes. All examples show wildcard at the end of the pattern. Can we place a wildcard in the middle of the pattern or have several wildcards in the same pattern? I checked that in the middle it works as expected but is it documented?

Yes, the index pattern match supports wildcards anywhere in the pattern, including multiple wildcards in the same pattern. It doesn't seem to be documented as such, here are the docs for index patterns: https://www.elastic.co/guide/en/elasticsearch/reference/current/multi-index.html