Steps to reproduce
Enter a tag like #abc_123.
Expected result
Tag should appear in tag list as abc_123.
Characters usually allowed in programming language identifiers like _ and @ should at least also be allowed in tag names.
Or why not in general take as a tag name all characters following a # up until the first whitespace character? Then tags like #library/books/mystery would at least be valid syntactically, even though the nesting is not recognized yet.
Actual result
Tag appears as abc.
Environment
Additional information