What feature helps prevent unauthorized copying of prescription forms?

Watermarking is a feature that significantly enhances the security of prescription forms and helps prevent unauthorized copying. Watermarks are identifiable designs or patterns that are embedded within the paper and are typically visible when held up to the light. This makes it challenging for counterfeiters to replicate the forms accurately, as the watermarking process is usually complex and requires specialized equipment.

In contrast, while serial numbers can assist in tracking prescriptions and maintaining order control, they do not inherently prevent copying. Uniform color or specific health warnings do not directly create barriers to unauthorized duplication. Therefore, watermarking stands out as an effective deterrent against the replication of prescription forms, ensuring that the authenticity of the document is maintained.