2.1.867 Part 1 Section 18.17.2.5, Names

a.   The standard does not use EBNF to write the syntax for name.

Office writes the productions for name using the following EBNF:

 name-reference= name |
   external-name;
 external-name= single-sheet-prefix, name;
 name=
   name-start-character, [ name-characters ]  ;
 name-start-character=
   underscore  |  backslash  |  ? any code points which are characters as defined by the Unicode character properties, chapter four of the Unicode Standard ?;
 underscore=
   "_"  ;
 backslash=
   "\"  ;
 name-characters=
   name-character,  {name-character}  ;
 name-character=
   name-start-character  |  decimal-digit  |  full-stop  |  ? any code points which are digits as defined by the Unicode character properties, chapter four of the Unicode standard ?;

b.   The standard specifies that two names that are the same in different workbooks can be disambiguated by prepending the workbook name.

Office prefixes names used in the same context with the index of the relationship ID associated with the workbook name and an exclamation mark. A relationship ID index of 0 indicates the current workbook.

c.   The standard does not specify that \name-character is an invalid name.

Office will not create or load names of the form \name-character.