What "null types"? It's just a null value. And why should quoted values be specially allowed to replace null current values but other values like numbers and true and false NOT be allowed. It seems like this code allows any value to be replaced by null, but only quoted values can then replace the null once it's in? So, fields are strongly typed unless/until you set them to null, at which point they become string typed? Do we think we're catching a lot of errors with this prior-value-based mostly-typing system or should we maybe just hang it up?