Searching SQL - Some queries missing?

Using Enterprise Manager 10.2.0.5.0, I'm rummaging through queries that have been executed and I've come across some oddities. 
(I've confirmed the same results by examining SYS.V_$SQLFULLTEXT directly).

• "create user" and "alter user" statements do not appear at all. 
  This probably makes sense because (a) they're like to have have passwords in them and (b) they're not going to have a huge impact on performance (unless you drop something important, of course!) but I'd still [naively] expect them to appear, if only for completeness.
  
  
• "set role" statements appear truncated to twenty characters, e.g.  "set role R2345678901", even though the actual statement submitted can be much longer.