Dick did a test of an Apache Ant task posting to ESME. The Ant task created a tag "Ant Task" (without quotes) via the API, which is allowed. But there is no way for me to use the same tag from the UI, as far as I can tell. Either tags from the API should be converted to a non-space format, or we should allow users to put spaces in their tags and then display the tag that way in the message input pane on the tag/TAGNAME view.
See postings under http://esmecloudserverapache.dickhirsch.staxapps.net/tag/Ant%20Task for example.