AtomName (PSZ) - input
This is a character string to be added to the table.
If the string begins with an "#" character, the five ASCII digits that follow are converted into an integer atom. If this integer is a valid integer atom, this function returns that atom, without modifying the atom table.
If the string begins with an "!" character, the next four bytes are interpreted as an atom. If it is an integer atom, that atom is returned. If it is not an integer atom and it is a valid atom for the given atom table (that is, it has an atom name and use count associated with it) the use count of that atom is incremented by one and the atom is returned. Otherwise 0 is returned.
If the high order word of the string is minus one, the low order word is an atom. If it is an integer atom, that atom is returned. If it is not an integer atom and it is a valid atom for the given atom table (that is, it has an atom name and use count associated with it) the use count of that atom is incremented by one and the atom is returned. Otherwise 0 is returned.