Possible Bug with -v grep flag

[Ramos, Jaime (H USA) (EXT)]

Is it true there is a restriction on syntax such as
 
grep -v a -v e -v i -v o -u T1.txt
 
 
 
from my experimentation it seems as if I can only invoke one -v flag at
once, without ANY other patterns, that we do want to match. To get
functionality like this I'm having to use the pipe command |
 
 
 
 
thanks
 
 
 
 
 
Jaime