Hi Axel,You can use Attibutes to add any kind of information you want to symbols.
Doubleclick on a symbol to display the Symbol Properties dialog which lists all attribute names and values. Values are editable - just doubleclick in the Value field. Attributes can be created if you click on the Modify button.
For more on Attributes, refer to the Help system and check out the Symbols topic, Attributes section.
I hope this is helpful.