GitHub GraphQL Ref Query Format

Question

In the GitHub API, there is an optional parameter when querying the refs object called query, which "Filters refs with query on name". Is the syntax for this query string documented somewhere? I would like to query refs that match the regular expression ^v\d+(\.\d+)+$ , but it seems regular expression syntax isn't supported. I've been successful with v[0-9], but can't figure out if there is a syntax for start/end anchors or multiplicity. I've searched the online documentation, but haven't found anything that sheds light on what syntax is allowed for this. For reference, this is my GraphQL query:

'query($owner:String!,$name:String!,$cursor:String){' +
 'repository(owner:$owner,name:$name){' +
 'refs(after:$cursor,first:100,' +
 'orderBy:{field:TAG_COMMIT_DATE,direction:DESC},' +
 'refPrefix:"refs/tags/",' +
 'query:"????"){' +
 'nodes{name,target{...on Commit{committedDate},...on Tag{tagger{date}}}}' +
 'pageInfo{hasNextPage,endCursor}' +
 '}'+
 '}' +
'}'