Up to WinCC V4.02:
the variable names of the archive variables include illegal signs such as ( / ).
As of WinCC V4.02:
if you use quotes ( " ) in the names of the project variables, those variables are not archived in Tag Logging.
Most other special characters are processed. As far as possible do not use any special characters in the names of the project variables. If you do use special characters, then test whether the variables concerned can actually be archived.
There are characters that Tag Logging converts automatically. For example, the Tag Logging editor converts hyphen ( - ) and hash ( # ) to underscore ( _ ).