"A fragment identifier component is indicated by the presence of a number sign ("#") character and terminated by the end of the URI"
Guess what is nowhere explicitly defined...
Right! The "end of the URI".
And No! It is not whitespace!
Because "In some cases, extra whitespace (spaces, line-breaks, tabs, etc.) may have to be added to break a long URI across lines. The whitespace should be ignored when the URI is extracted."
