Understand the observation method
| Family | Concept | Ordinary-image limit |
|---|---|---|
| Printed details | Fine patterns and controlled printing techniques | Compression can obscure small details |
| Optically variable features | Appearance changes under different viewing conditions | A single fixed image does not show a change |
| Material or embedded features | Properties associated with the physical substrate | A scan does not reproduce material properties |
| Machine-assisted checks | Signals inspected with an appropriate reader or system | Visible pixels do not substitute for the check |
PRADO's glossary describes terms such as watermark, security thread and optically variable features. These are descriptions of feature classes, not a promise that a particular document contains all of them. PRADO glossary of document-security terms
A reference-driven review
- Locate the exact document edition in an authoritative reference.
- List the feature and the observation method the reference describes.
- Decide whether the available image or equipment can support that method.
- Record “not assessed” when the evidence channel is missing.
- Escalate interpretation when it exceeds your training or approved role.
Suppose a reference describes a feature that changes as a page is tilted. A flat scan may show one appearance. It cannot establish the described change. The appropriate finding is that the change was not observed by this method, not that the feature is absent.
Keep education separate from replication
Learning why a feature matters does not require a replica. This site explains evidence limits and observation concepts. It does not provide manufacturing instructions, issuer artwork, production parameters or downloadable government-document layouts.