FYI, DOCUMENTS API Help contains a link to this topic but does not mention it by name.
Validation enables you to:
Ensure the accuracy and consistency of document data.
Add, change, or remove data.
Change the status of documents.
Redirect a document for special processing.
Set up basic validation in field specifications. Available settings:
Value range.
Table validation using a table that you created according to the instructions. (You can also translate field values using such a table.)
Specifying the extraction format for more information.
Basic validation is not the same as format extraction. See
You can add rules to:
Field specifications or templates (including compound field specifications)
These rules only apply to the field you configure in the field specification.
Documents and other objects (such as compounds and batches)
These rules allow you to establish relations between different fields within the document, compound document, or batch specification. For example, Total Amount = Net amount + Tax amount.
Invoice solutions that use the Invoice modules can include invoice-specific field validations.