Is there a list of characters allowed to define a principal name and realm?

[Julio Cesar Parra/Mexico/IBM]

Hola.. 

I'm defining some documentation of this two terms (principal name and 
realm). And I'm wondering if there is any special characters allowed to 
define a principal name and realm name ?

I know that the valid characters are case sensitive and include all 
alpha-numeric characters (a-z, A-Z, 0-9). but I need to know if there are 
more special characters that need to be considered.

Thanks in advance.


*  Carpe diem
Julio Cesar Parra Uribe    IBMMX(JCPARRA) 
E-mail:   jcparra at mx1.ibm.com 
T/L   877-2535 Ext phone:  (5233)3669-7000  Ext.  2535