Optional parameter

[Manuel Martins]

Hello,

I have a situation where I'm parsing a file, line #1 can be can be either A or B, if line #1 is A then line #2 is B, however line #1 can be be B

Example 1 -  

  A|xx|xx

  B|xx|xx

  C|xx|xx

Example 2 -

  B|xx|xx

  C|xx|xx

How can I create a Parser that will allow for optional value?  I also want to get the value for A & B  returned.

Any help or direction would be greatly appreciated.

Thank you,

Manny