For each PDF/A-1 validation issue we try to explain what it means and, if possible how to resolve it. For a more technical explanation of the issue we quote the related section of the ISO 19005-1 PDF/A Specification.
All extension schemas used in a conforming file shall have their descriptions embedded within that file in the metadata stream defined by 6.7.2. These descriptions shall be specified using the PDF/A extension schema description schema defined in this clause. NOTE 1: An extension schema is any XMP schema that is not defined in XMP Specification. The extension schema description schema defined in Table 2 uses the namespace URI <http://www.aiim.org/pdfa/ns/schema>. The required schema namespace prefix is pdfaSchema. NOTE 2: According to the W3C XML Namespace recommendation [18], namespace URI’s are for identification purposes only and are not required to be actionable links. None of the namespace URI’s defined for XMP extension schemas in this part of ISO 19005 is an actionable link. Attempting to dereference or follow any of these links will not result in a valid web page. Table 2 — PDF/A extension schema description schema
Property
Value type
Category
Description
pdfaSchema:schema
Text
External
Optional description of schema
pdfaSchema:namespaceURI
URI
External
Schema namespace URI
pdfaSchema:prefix
Text
External
Preferred schema namespace prefix
pdfaSchema:property
seq Property
Internal
Description of schema properties
pdfaSchema:valueType
seq ValueType
Internal
Description of schema-specific value types
The Property type defined in Table 3 is an XMP structure containing the description of a schema property. The field namespace URI is . The required field namespace prefix is
pdfaProperty. Table 3 — PDF/A property type schema
Field name
Value type
Description
pdfaProperty:name
Text
Property name
pdfaProperty:valueType
Open Choice of
Text
Value type of the property, drawn from XMP Specification 4, or
an embedded PDF/A value type extension schema
pdfaProperty:category
Closed Choice of Text
Property category: internal or external
pdfaProperty:description
Text
Description of the property
The preferred values for pdfaProperty:valueType should be the non-deprecated property value types defined in XMP Specification 2004, 4. Array types shall be preceded by their container type: alt, bag or seq, separated from the base type by a single white-space character.
The ValueType type defined in Table 4 is an XMP structure containing the description of all property value types used by embedded extension schemas that are not defined in XMP Specification 4. The field namespace URI is <http://www.aiim.org/pdfa/ns/type>. The required field namespace prefix is pdfaType. Table 4 — PDF/A value type schema
Field name
Value type
Description
pdfaType:type
Text
Property value type name
pdfaType:namespaceURI
URI
Property value type field namespace URI
pdfaType:prefix
Text
Preferred value type field namespace prefix
pdfaType:description
Text
Description of the property value type
pdfaType:field
seq Field
Optional description of the structured fields
The Field type defined in Table 5 is an XMP structure containing the description of a property value type field. The field namespace URI is . The required field namespace prefix is
pdfaField. Table 5 — PDF/A field schema
Field name
Value type
Description
pdfaField:name
Text
Field name
pdfaField:valueType
Open Choice of Text
Field value type, drawn from XMP Specification 2004, 4, or an embedded PDF/A value type extension schema