Conditional signature points
Prerequisites
A pair of API key ID and API key secret.
Some credits for the Document Simple Forensic API, the Document Simple API, or the Document Advanced API workflow.
Sometimes you would like to define signature processes where the signer can choose where to sign instead of signing in all defined places automatically.
For example, a contract with some optional clauses that require a signature in the document in case of acceptance.
For cases like this, you could use the conditional signatures.
Let’s go straight away into a signature creation payload. Each document in the signature creation payload, can have an additional conditionalSignatures field, for example
....
conditionalSignatures: [{
name: "optional_caluse",
text: "Accepting this optional clause you will receive loads of messages",
required: false,
signatureFieldsName: ["opt_sig1"],
alert: "Are you sure you want to sign this!?"
}]
....As you can see, conditional signatures are very similar to signatures; the main difference is that they require an explicit action from the signer.
The following screenshots show a signing environment with multiple documents, some of which have conditional signatures.

Opening the first document.

You can see two signature fields. The last one is associated with the conditional signature identified by A. These identifiers are automatically generated by Web Trust and allow you to visually link the condition with the signature field inside the PDF file.
Once you check this required condition, see the * at the end of the text; you will see an alert.

This alert was configured in the creation payload.
You can have more than one condition per document.

You can declare here multiple disjoint subsets of signature fields where the signature will be placed only if the signer accepts associated terms. If the subsets have signature fields in common, there is no predefined behaviour on which conditional takes precedence.
If the conditional doesn't match any signature field in the PDF, the request will fail validation with a 400 error.
All the fields used for the conditional signatures must be Acrofields of type Signature.