Add a text caption to Electronic Seal Fields

You can now add a text caption directly inside an Electronic Seal Field area using the new captions parameter on POST /v3/electronic_seals (see API reference).

The caption is rendered below the seal image, within the same Field area. It is useful to display a short label tied to the seal visual — such as a department name or internal reference — without placing a separate read_only_text Field next to it. Unlike read_only_text, it can be used on already-signed documents without breaking prior signatures.

Key constraints:

• captions accepts an array with exactly one entry.
• text must not exceed 150 characters.
• Font size is calculated automatically to fit the available space; adjust the size of your image, width or height parameters to control line wrapping.
• The parameter is optional, omit it entirely to render no caption.

For full details, see the Add Caption to your Electronic Seal guide.