Hi George,

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By defintion a null string has a data type, a null does not.
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This is correct.

But VFP is not a good reference for explain this.

=NULL  && this is a null, without data type
release x
x=NULL && this is a Logical NULL
x=''   && this is a empty string
x=NULL && now x is a null string
? VARTYPE(m.x,.T.),TYPE('m.x')
? VARTYPE(m.x) && return 'X', but it is a trick
* in fact
? NULL+1 && return a null value
? m.x+1  && fire a error because you cannot concat a null string with a number

Fabio