Shell Programming and Scripting

Hello everyone. I am new to unix, nice to meet you all.
I have a small problem with a question.
I have to write a command that finds all the postal codes in a txt file. All postal codes will begin on its own line in the txt file.
This is the formal of postal code: "A#A#A#" or "A#A #A#"
A being a letter and # being a number. Letters D F I O Q and U are restricted.
My problem is how to reconize the optional space in the middle. Here is what I have so far:
grep "^[WERTYPASGHJKLZXCVBNM][1-9][WERTYPASGHJKLZXCVBNM]{1-9,:space:1-9}[WERTYPASGHJKLZXCVBNM][1-9]" address.txt

The red part being the wrong part, could anyone help? thank you so much.

Code:

$ 
$ 
$ cat -n f14
     1    A1B2C3
     2    D4E 5F6
     3    G7H8I9
     4    J0K 1L2
     5    M3N4O5
     6    P6Q 7R8
     7    S9T0U1
     8    V2W 3X4
     9    Y5Z6A7
$ 
$ x="[ABCEGHJKLMNPRSTVWXYZ]"
$ 
$ grep "^$x[0-9]$x[ ]*[0-9]$x[0-9]$" f14
A1B2C3
J0K 1L2
V2W 3X4
Y5Z6A7
$ 
$ 

tyler_durden

grep -E "^[WERTYPASGHJKLZXCVBNM][1-9][WERTYPASGHJKLZXCVBNM][[:space:]]?[1-9][WERTYPASGHJKLZXCVBNM][1-9]" address.txt

You were going well. The [[:space:]] can be substituted for just a literal space or a [ ] in your case.

thanks fight club and Aia. With your help i got this question done