However, the full name of the film will not fit into the 25 character limit (until we get an extension, which seems to be an experiment on other sites now). Which tag should we use for the film? (e.g. valerian-and-the-city, valerian-2017, etc.) Please keep in mind that the tag should be easy to autocomplete (so that it's easy to find), and fit into the character limit, while at the same time looking sane (preferably without awkward abbreviations).
Given the extraordinary unlikelihood of a sequel, the absence of other properties called "Valerian" and the need to distinguish it from the comic serials, the tag valerian-2017 would seem more than adequate.
Note that when searching, the letters "valer" will offer only one other option, so this seems the obvious and simple choice.
After the increased tag limit there is chance for a better descriptive tag name and I suggest :