It thorws me off base when String.IndexOf finds a matching string at the beginning of the string and returns 0 (zero) as the position.

Ex:

String aString = "L1 OR L3 or L2"

What would be the value from, aString.IndexOf("L1")? It is 0.

As per MSDN documentation,

The index position of value if that string is found, or -1 if it is not. If value is Empty, the return value is 0. - This does not seem right?

It makes sense, if the value is empty ( example: String.IndexOf() ) then the return value is 0.

In your case aString.IndexOf("L1") should return 0 since C# uses 0 based indices.

Use an if statement if you want to catch the case where the value is 0.

Example:
if ( value.Length() == 0 )
    //Do something
else
    location = aString.IndexOf( value );

- A.Kahtava

That's what I endup doing though!

Thank you.