Usernames

A "username" is the filename of the Myfile, seen after the "//" in a Myfile address.

Usernames:

• can have alphanumeric characters (i.e. [0-9a-zA-Z])
• can have parentheses (( and )), brackets ([ and ]), curly braces ({ and }), apostrophes and simple quotes (' and "). They do not have to match.
• can have the less-than (<) and greater-than (>) symbols.
• cannot have emoji. They can be represented in the xn--... punycode form.
• can be any (reasonable) length. They must be at least one character, for blank usernames refer to the domain.
• can have the plus +, minus -, ampersand ("and" sign) &, asterisk *, forward-slashes / (these are not used for navigation past the // in the path), tildes ~, underscores (underlines) _, periods ., commas ,, question marks ?, and exclamation points !.
• cannot have backslashes (\). This is to allow them to escape curly braces that may be in the address.
• cannot have two successive forward-slashes, such as //. This is used to separate the path from the username.