IsValidReturns 0 (False) if:
• FileMaker Pro cannot locate (temporarily or permanently) the related table in which the referenced field is definedOtherwise, it returns 1 (the data is valid).Note IsValid does not check field validation options defined in the Manage Database dialog box. Define field validation options to make sure that data is correctly entered into fields during data entry and import. See Defining field validation.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.