14. Document interchange

14.5 Page-piece dictionaries

Change the paragraph above Table 350 as follows:

As "Table 350 - Entries in a page-piece dictionary" shows, a page-piece dictionary may contain any number of entries, each keyed by key should be a second-class name, or the name of a distinct PDF processor, or of a well-known data type recognised by a family of PDF processors. The value associated with each key shall be a data dictionary containing the private data that shall be used by the PDF processor. The Private entry may have a value of any data type, but typically it is a dictionary containing all of the private data needed by the PDF processor other than the actual content of the document, page, or form.

Change Table 350 as follows:

Table 350 - Entries in a page-piece dictionary
Key Type Value
any valid second-class name (recommended), any conforming product name or well known data type dictionary A data dictionary (see "Table 351 - Entries in a data dictionary").

Insert new NOTE below Table 350 as follows:

NOTE: the definition of page-piece dictionary keys was updated to also support the same definition as in ISO 32000-1:2008 to allow easier document upgrades to PDF 2.0, however second-class names are strongly recommend.

14.6 Marked content

14.6.1 General

Change NOTE 3 as follows:

NOTE 3 The tag operand of marked-content operators have no relationship to Tagged PDF (see 14.8 "Tagged PDF") and thus is not rolemappedrole mapped.

14.7 Logical structure

14.7.2 Structure hierarchy

Change Table 355 as follows:

Table 355 - Entries in a structure element dictionary
Key Type Value
R integer (Optional; deprecated in PDF 2.0) The current revision number of this structure element (see 14.7.6.3, "Attribute revision numbers"). The value shall be a non-negative integer. Default value: 0.

14.7.3 Structure types

Change the third paragraph as follows:

The RoleMap dictionary shall be comprised of a set of keys representing structure element types rolemappedrole mapped to other structure element types. The corresponding value for each of these keys shall be a single name identifying the target structure element type.

...

14.8 Tagged PDF

14.8.4 Standard structure types

14.8.4.4 Grouping level structure types

Change Table 365 as follows:

Table 365 - Grouping level structure types
Structure Type Category Description
Part Grouping

Encloses a grouping of structure elements without consideration for their hierarchy.

NOTE 1 Part is the semantic equivalent of Div The non-hierarchical aspect of Part is similar to Div. However, unlike Div, the grouping of elements enclosed in a Part structure element has semantic value..

A structure element with the type of Part shall inherit the containment requirements and limitations of its parent element. Where the parent element is itself a structure element of type Part, then the inheritance shall recurse to the first parent element whose type is not Part.

NOTE 2 The semantic value of a structure element of type Part is determined by the elements enclosed within, in addition to the grouping nature of Part.

...

14.8.4.7 Inline level structure types

14.8.4.7.2 General inline level structure types

Change Table 368 as follows:

Table 368 - General inline level structure types
Structure Type Category Description
Strong Inline

(PDF 2.0) Encloses content for the purpose of strong importance, seriousness or urgency for its contents.

EXAMPLE 3 In this example the Strong element is used to denote the content that the user is intended to read first is more important:

...

Insert a new clause heading below NOTE 1 and modify text as follows:

14.8.4.7.3 Link elements

Tagged PDF link elements (standard structure type Link) use PDF's logical structure facilities to establish the association between content items and link annotations, providing functionality comparable to HTML hypertext links. The following items may be children of a link element:

  • One or more content items or other ILSEs (except other links) if A, Dest and PA keys of all of them have identical values
  • Object references (see 14.7.5.3, "PDF objects as content items") to one or more link annotation annotations associated with the content

NOTE 21 An SD entry in the GoTo or GoToR action in a Link annotation facilitates linking directly to a target structure element as opposed to just targeting an area on a page.

When a Link structure element describes a span of text to be associated with a link annotation and that span wraps from the end of one line to the beginning of another, the Link structure element shall include a single object reference that associates the span with the associated link annotation. Further, the link annotation shall use the QuadPoint entry to denote the active areas on the page.

EXAMPLE 1 The Link structure element references a link annotation that includes a QuadPoint entry that boxes the strings "with a" and "link". That is, the QuadPoint entry contains 16 numbers: the first 8 numbers describe a quadrilateral for "with a", and the next 8 describe a quadrilateral for "link".

Here is some text with a
link inside.

NOTE 2 Beginning with PDF 1.7, use of the Link structure element to enclose multiple link annotations on a single page is deprecated.

EXAMPLE 2 Consider the following fragment of HTML code, which produces a line of text containing a hypertext link:

<html> <body> <p> Here is some text <a href="https://www.pdfa.org">with a link</a> inside. </p> </body> </html>

This code sample shows an equivalent fragment of PDF using a link element, whose text it displays in blue and underlined.

/P << /MCID 0 >> % Marked-content sequence 0 (paragraph) BDC % Begin marked-content sequence BT % Begin text object /T1_0 1 Tf % Set text font and size 14 0 0 14 10.000 753.976 Tm % Set text matrix 0.0 0.0 0.0 rg % Set nonstroking colour to black (Here is some text ) Tj % Show text preceding link ET % End text object EMC % End marked-content sequence /Link << /MCID 1 >> % Marked-content sequence 1 (link) BDC % Begin marked-content sequence 0.7 w % Set line width [ ] 0 d % Solid dash pattern 111.094 751.8587 m % Move to beginning of underline 174.486 751.8587 l % Draw underline 0.0 0.0 1.0 RG % Set stroking colour to blue S % Stroke underline BT % Begin text object 14 0 0 14 111.094 753.976 Tm % Set text matrix 0.0 0.0 1.0 rg % Set nonstroking colour to blue (with a link) Tj % Show text of link ET % End text object EMC % End marked-content sequence /P << /MCID 2 >> % Marked-content sequence 2 (paragraph) BDC % Begin marked-content sequence BT % Begin text object 14 0 0 14 174.486 753.976 Tm % Set text matrix 0.0 0.0 0.0 rg % Set nonstroking colour to black ( inside.) Tj % Show text following link ET % End text object EMC % End marked-content sequence

EXAMPLE 3 This example shows an excerpt from the associated logical structure hierarchy.

501 0 obj % Structure element for paragraph << /Type /StructElem /S /P ... /K [ 0 % Three children: marked-content sequence 0 502 0 R % Link 2 % Marked-content sequence 2 ] >> endobj 502 0 obj % Structure element for link << /Type /StructElem /S /Link ... /K [ 1 % Two children: marked-content sequence 1 503 0 R % Object reference to link annotation ] >> endobj 503 0 obj % Object reference to link annotation << /Type /OBJR /Obj 600 0 R % Link annotation (not shown) >> endobj

14.8.4.7.34 Ruby and warichu elements

EDITOR NOTE: Clause is renumbered - existing text is unchanged.

14.8.4.8.3 Table structure types

Change Table 371 as follows:

Table 371 - Table standard structure types
Structure Type Category Description
TR Internal to a Table structure A row of table header cells (TH) or table data cells (TD) or both in a table.
14.8.4.8.4 Caption structure types

Change Table 372 as follows:

Table 372 - Standard structure type Caption
Structure Type Category Description
Caption Grouping or Block

...

A structure element is understood to be "captioned" when a Caption structure element exists as an immediate child of that structure element. The Caption shall be the first or the last structure element inside its parent structure element. The number of captions cannot exceed 1.

While captions are often used with figures or formulas, they may be associated with any type of content.

NOTE 1 In principle, captions can appear in a nested fashion. For example, several smaller images belonging to a group of images can each be accompanied by a caption, and the group of these images as a whole is accompanied by a caption as well.

NOTE 2 If an Artifact structure element is present, and needs to be associated with a Caption, then the Artifact structure element needs to be a descendent of the Caption.

14.8.5 Standard structure attributes

14.8.5.4 Layout attributes

14.8.5.4.2 General layout attributes

Change Table 378 as follows:

Table 378 - Standard layout attributes common to all standard structure types
Key Type Value
Placement name

(Optional; not inheritable) The positioning of the element with respect to the enclosing reference area and other content (see 14.8.3.3, "Progression direction"). The value shall be one of the following:

...

Default value: Block for BLSEs, Inline for ILSEs.

NOTE The default value depends on the context in which the structure element is used (see 14.8.4.1, "General").

EXAMPLE 1 A Figure structure element occurring within a P structure element is an ILSE, and therefore has a default value of Inline.

EXAMPLE 2 A Figure structure element occurring within a Sect structure element is an BLSE, and therefore has a default value of Block.

WritingMode name

(Optional; inheritable) Indicates the directions of layout progression inside Block Level Structure Elements (BLSEs) (inline progression) and regarding the sequence of BLSEs (block progression) (see 14.8.3.3, "Progression direction"). WritingMode may be used as an attribute for any structure element. The value shall be one of the following:

...
14.8.5.4.4 Layout Attributes for ILSEs

Change Table 380 as follows:

Table 380 - Standard layout attributes specific to inline-level structure elements
Key Type Value
GlyphOrientationVertical numberinteger or name

...

14.8.6 Standard structure namespaces

14.8.6.1 Namespaces for standard structure types and attributes

Modify the paragraph above the current NOTE as follows:

To facilitate conversion of documents created against versions of the PDF standard earlier than PDF 2.0, the default standard structure namespace shall be "http://iso.org/pdf/ssn". When a namespace is not explicitly specified for a given structure element or attribute, it shall be assumed to be within this default standard structure namespace. When a structure element does not have a specified namespace, after transitively applying any role map present (see 14.8.6.2, "Role maps and namespaces"), the final element type shall be considered to be within the default standard structure namespace and shall be one of the standard structure types defined in the default standard structure namespace.

Add a new NOTE 1 above the current NOTE as follows:

NOTE 1 The original structure type is still considered to be in an undefined namespace, which means it is exempt from restrictions on role mapping within the same namespace.

EDITOR NOTE: the current note is renumbered as NOTE 2.

Insert a new NOTE 3 after the last paragraph as follows:

The term standard structure namespaces refers to either of the two namespaces defined above.

NOTE 3 Namespaces are designed to provide greater interchange of PDFs including logical structure, providing a means to identify the custom namespace for each element, if appropriate. However, structure elements types in undefined namespaces continue to be permitted.

14.8.6.2 Role maps and namespaces

...

Modify the 2nd bullet in the bulleted list as follows:

In a tagged PDF, all structure elements shall be in at least one of the standard structure namespaces or in a namespace identified in 14.8.6.3, “Other namespaces”. An element shall be considered to be in one of these namespaces if:

  • they directly identify one of these namespaces through their NS entry;
  • they are in the default standard structure namespace (after any role mapping);
  • ...

Insert a new EXAMPLE 1 at the end of the subclause as follows:

EXAMPLE 1: use of namespaces

17 0 obj << /Type /StructElem /S /section /P 5 0 R /NS 15 0 R >> endobj 15 0 obj << /Type /Namespace /NS (urn:uuid:A63861E-9F7-4FCB-9B27-C3BC8D9BFB06) /RoleMapNS 16 0 R >> endobj 16 0 obj << /section [/H1 11 0 R] ... >> endobj

Insert a new EXAMPLE 2 at the end of the subclause as follows:

EXAMPLE 2: Role mapping of structure elements with no explicitly identified namespace

13 0 obj % A structure tree with a role map for elements within an undefined namespace << /Type /StructTreeRoot /RoleMap << % The "Global" role map is applied to elements in an undefined namespace. /Foo /Bar % The element type "Foo" in an undefined namespace maps to "Bar". /Bar /P % The "Bar" element in an undefined namespace maps to P, which is defined in % the default standard structure namespace. This means that elements of % type "Foo" transitively map to "P" through the "Bar" element type. >> ... >> endobj 14 0 obj % A structure element with an undefined namespace of structure type "Foo" << /Type /StructElem % Structure Element with no defined namespace. /S /Foo % The "Foo" element has an undefined namespace and isn't defined in either % the PDF 1.7 or PDF 2.0 namespaces. ... >> endobj

14.8.6.3 Other namespaces

Replace the paragraph below NOTE 1 as follows:

NOTE 1 MathML is the only domain-specific namespace defined in PDF 2.0.

When including mathematics structured as MathML 3.0, the math structure element type as defined in MathML 3.0 shall be used, and shall have its namespace explicitly defined (see 14.7.4.2, "Namespace dictionary"). When including mathematics structured as MathML 3.0, the math structure element type, as defined in MathML 3.0, shall be used to enclose the formula under the Formula structure element type. All MathML structure element types and their attributes shall have the MathML 3.0 namespace explicitly defined (see 14.7.4.2, "Namespace dictionary").

...

14.12.4.2 Document part metadata

Change the last paragraph as follows:

The values of keys present in the DPM dictionary, or of any dictionary or array object present in the DPM dictionary, shall only be of type text string, date string, name, array, dictionary, boolean, integer or real as defined in 7.3, "Objects". All key values that are PDF name objects, after expansion of character sequences escaped with a NUMBER SIGN (23h), if any, shall be valid UTF-8 character sequences. Other PDF value types shall not be used.

14.13.5 Associated files linked to graphics objects

Change the paragraph below NOTE 3 as follows:

The property list associated with the marked-content shall specify an array of file specification dictionaries to which the content is associated. The named resource in the Property List property list (see 14.6.2, "Property lists") shall specify an array of file specification dictionaries to which the content is associated. The relationship that the associated files have to the PDF content is supplied by the AFRelationship key in each file specification dictionary.

...

Last modified: 1 July 2022