PDF/A-1a is with conformance level A (for "accessibility"), and must adhere to all of the requirements of the PDF Reference as modified by the ISO 19005 specification. 

It requires structural and semantic properties to be preserved. Level 1a uses “Tagged PDF” and Unicode character maps to preserve the document's logical structure and content text stream in natural reading order. 

The following features are used:
- Language specification
- Hierarchical document structure
- Tagged text spans and descriptive text for images and symbols
- Character mappings to Unicode

The purpose is to improve accessibility and make the content accessible for screen readers.

For complienace level PDF/A-2a please follow: PdfProcessing: Add support for PDF/A-2a compliance level.

The currently supported compliance levels can be found in the How to Comply with PDF/A Standard article.

Currently the DocumentInfo property is for export purposes only and meta information about documents is stripped when importing.

According to the PDF specification (ISO 32000), the document info dictionary (often called "metadata" or "Info" dictionary) can include the following standard fields:

• Title: The document’s title.
• Author: The name of the person who created the document.
• Subject: The subject of the document.
• Keywords: Keywords associated with the document.
• Creator: The application that created the original document.
• Producer: The application that converted the document to PDF.
• CreationDate: The date and time the document was created.
• ModDate: The date and time the document was last modified.
• Trapped: Indicates whether the document has been trapped (a printing term).

These fields are stored in the PDF’s Info dictionary and are used by PDF viewers for display, search, and indexing.

 

Purpose: Long-term archiving of electronic documents with full semantic structure.

• "A" for Archiving

• Level "1a" ensures:

  • Tagged PDF (with proper logical structure and reading order)

  • Unicode text for proper text extraction and searchability

  • Embedded fonts (for consistent rendering)

• Restrictions:

  • No audio/video

  • No encryption

  • No JavaScript

  • No external content (everything must be self-contained)

• Based on: PDF 1.4 (Acrobat 5)

Part 3 of the standard, published on October 15, 2012, differs from PDF/A-2 in only one regard: it allows embedding of arbitrary file formats (such as XML, CSV, CAD, word-processing documents, spreadsheet documents, and others) into PDF/A conforming documents.

PDF/UA (PDF/Universal Accessibility) is the informal name for ISO 14289, the International Standard for accessible PDF technology.

The PDF/A-1 standard uses the PDF Reference 1.4 and specifies two levels of compliance:

- PDF/A-1b - Its goal is to ensure reliable reproduction of the visual appearance of the document.

- PDF/A-1a - Its objective is to ensure that documents content can be searched and re-purposed. This compliance level has some additional requirements:

• Document structure must be included.
• Tagged PDF.
• Unicode character maps
• Language specification.

Since the PdfProcessing and its PdfFormatProvider is compliant with the PDF Reference 1.7. , the produced documents are created with this version as well: 

Implement Viewer related properties in PdfProcessing in order to enable the users to set PrintScaling, Duplex, and other properties which are written in the Pdf Format specification as Interactive Features. 

ViewerPreferences are written a document's catalog. Check p.577 from pdf reference format specification, version 1.7

It would be great if the SkiaImageExportSettings offer a DocumentUnhandledException event allowing the developer to handle specific errors when exporting to image formats.

This would be an essential improvement in the existing Exception handling mechanism and would enable exporting PDF documents to images even though some parts of the image may not be completely supported: https://docs.telerik.com/devtools/document-processing/libraries/radpdfprocessing/features/handling-document-exceptions 

Handle documents with mismatched font Subtype and FontFile type when exporting PDF to image with SkiaImageFormatProvider.

At this point the culture used by RadSpreadProcessing (in the FormatHelper and internally in SpreadsheetCultureHelper) is determined by the current thread culture on startup. Provide ability to:
- to change the culture at runtime. Currently, when the thread culture is changed, RadSpreadProcessing is "stuck" with the original one.
- set this culture independently of the current thread's one.

The standard fonts listed at http://docs.telerik.com/devtools/wpf/controls/radpdfprocessing/concepts/fonts#standard-fonts cannot be embedded in a document. Using one of them prevents the document from complying with PDF/A standard.

When importing a document with an invalid creation or modification date, an exception is thrown:

• FormatException: 'The input string '' was not in a correct format.'
• ArgumentOutOfRangeException: 'Year, Month, and Day parameters describe an unrepresentable DateTime.'

From the Part 4: PAdES Long Term - PAdES-LTV Profile (ETSI TS 102 778-4) Specification: 

"Validation of an electronic signature requires data to validate the signature such as CA certificates, Certificate Revocation List (CRLs) or Certificate status information (OCSP) commonly provided by an online service (referred to in the present document as validation data). If the document is stored and the signatures are to be verifiable long after first created, in particular after the signing certificate has expired, the original validation data may no longer available or there may uncertainty as to what validation data was used when the document was first verified."

Implement GetColor method for IndexedColorSpaceObject.

In Excel formulas, the double minus (--) is known as the "double unary operator." Its main purpose is to convert Boolean values (TRUE/FALSE) into numeric values (1/0).
How it works:
• TRUE becomes 1
• FALSE becomes 0
Example: Suppose you have an array formula like:

=SUM(--(B2:B20="Gamma"))

• (B2:B20="Gamma") produces an array of TRUE/FALSE.
• --(B2:B20="Gamma") converts that array to 1/0.
• SUM(...) then adds up the number of matches.

Some Excel functions (like SUM, SUMPRODUCT) require numbers, not Booleans.
The double unary is a concise way to force this conversion.

 

 

SEARCH function with the following format is valid only in Excel 365/2021 or later (with dynamic array support).
"=SEARCH({"Alpha","Beta","Gamma","Delta","Omega","Sigma","Zeta"}, "Omega")"

• It returns an array of numbers or errors, showing the position of each substring in "Omega".
• If a substring is found, you get its position (e.g., 1 for "Omega"); if not, you get #VALUE!.

Add support for the RANDBETWEEN function.

Handle the import of documents when the GoToR action`s file specification object is a string.

Provide the ability to work with images in headers/footers of a worksheet. Note that large images put in headers are visualized as watermarks on printing/exporting to PDF.
Watermark in Excel: https://support.office.com/en-us/article/add-a-watermark-in-excel-a372182a-d733-484e-825c-18ddf3edf009