IsValid
Purpose 
Returns 0 (False) if the data is invalid and 1 (True) if the data is valid.
Format 
IsValid(field)
Parameters 
field - any field name
Data type returned 
number
Originated in 
FileMaker Pro 6.0 or earlier
Description 
Returns 0 (False) if:
 •
A record contains an invalid value because of a field type mismatch (text in a date field, for example)
 •
FileMaker Pro cannot locate (temporarily or permanently) the related table in which the referenced field is defined
 •
Otherwise, it returns 1 (the data is valid).
Examples 
IsValid(Datefield) returns 0 if there is non-date data in Datefield, for example if text was imported into it.
IsValid(Amount) returns 0 if there is only text in the number field Amount.
IsValid(table::field) returns 0 if the related table was renamed and the relationship isn’t updated with the new filename.
Related topics 
Functions reference (category list)
Functions reference (alphabetical list)
About formulas
About functions
Defining calculation fields
Using operators in formulas