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Missing-value functions take various numeric arguments and yield various types of results. Except where otherwise stated below, the normal rules of evaluation apply within expression arguments to these functions. In particular, user-missing values for numeric variables are converted to system-missing values.

- Function:
**MISSING***(*`expr`) When

`expr`is simply the name of a numeric variable, returns 1 if the variable has the system-missing value or if it is user-missing. For any other value 0 is returned. If`expr`takes another form, the function returns 1 if the value is system-missing, 0 otherwise.

- Function:
**NMISS***(*`expr`[,`expr`]…) Each argument must be a numeric expression. Returns the number of system-missing values in the list, which may include variable ranges using the

syntax.`var1`TO`var2`

- Function:
**NVALID***(*`expr`[,`expr`]…) Each argument must be a numeric expression. Returns the number of values in the list that are not system-missing. The list may include variable ranges using the

syntax.`var1`TO`var2`

- Function:
**SYSMIS***(*`expr`) Returns 1 if

`expr`has the system-missing value, 0 otherwise.

- Function:
**VALUE***(*`variable`) Prevents the user-missing values of

`variable`from being transformed into system-missing values, and always results in the actual value of`variable`, whether it is valid, user-missing, or system-missing.