2.1.7.17 User Names Stream (User Names)
The User Names Stream specifies a user log (section 2.2.11.1) for a shared workbook (section 2.2.11).
The name of this stream MUST be "User Names". The presence of the User Names Stream indicates the workbook is a shared workbook (section 2.2.11). A file MUST contain at most one User Names Stream.
Record sequence ABNF: