[ale] [OT] Regular Expression Help

[charriglists at bellsouth.net (Calvin Harrigan)]

Hi guys, I really hate having to bring up something so off topic, but I 
need a little help with regular expressions.
I have the following strings that I need to extract the optional letter 
after the second number.

     1    115       8:20

     2    113 U     8:21

     3    119 O     8:22

     4    115       8:26

     5    115       8:26

     6    115 T     8:27

line 2  = 'U'
line 3  = 'O'
line 4  = ''

I have the this expression, which does what I need it to:

^\s*\d*\s*\d*\s*(?<WeightMod>\w*)\s*\d+\:\d+

It extracts the letters just fine. For the lines that there isn't a 
letter, it returns an empty string, which is expected.
Is there any way to substitute another string when there is no letter to 
be captured?

i.e;
line 4 = 'N'

   I've been looking for a solution since yesterday, can't quite seem to 
pin it down.


Thanks