In this article Rod Paddock explains how to build a custom data type. I was wondering if anyone has built, or thinks it's a good idea to build, a custom data type of date, VFP style?

http://www.eps-cs.com/VFPConversion/Article.aspx?quickid=0303052

My understanding is that in SQL Server we have a DateTime data type, and it can't be empty. It seems like it would make upsizing simpler to be able to define a Date type and have it work as it does in VFP. This custom data type would give us one fewer thing to check when converting to SQL Server 2005.
When a CloseDate is empty, it conveys the information that the identity hasn't closed. When a CloseDate is NULL, it conveys that the identity may or may not be closed and if it is closed, we don't know when. Having the possibility for a date field to be filled, null, or empty seems right to me.