enow.com Web Search

Search results

  1. Results from the WOW.Com Content Network
  2. PDF - Wikipedia

    en.wikipedia.org/wiki/PDF

    HTML Form format HTML 4.01 Specification since PDF 1.5; HTML 2.0 since 1.2 Forms Data Format (FDF) based on PDF, uses the same syntax and has essentially the same file structure, but is much simpler than PDF since the body of an FDF document consists of only one required object. Forms Data Format is defined in the PDF specification (since PDF 1.2).

  3. List of open file formats - Wikipedia

    en.wikipedia.org/wiki/List_of_open_file_formats

    An open file format is a file format for storing digital data, defined by a published specification usually maintained by a standards organization, and which can be used and implemented by anyone. For example, an open format can be implemented by both proprietary and free and open source software , using the typical software licenses used by each.

  4. Astigmatism - Wikipedia

    en.wikipedia.org/wiki/Astigmatism

    Against-the-rule astigmatism – the horizontal meridian is steepest (a rugby ball or American football standing on its end). [17] Oblique astigmatism – the steepest curve lies in between 120 and 150 degrees and 30 and 60 degrees. [17] Irregular astigmatism – principal meridians are not perpendicular.

  5. Corrective lens - Wikipedia

    en.wikipedia.org/wiki/Corrective_lens

    Effects of astigmatism. As the eye shifts its gaze from looking through the optical center of the corrective lens, the lens-induced astigmatism value increases. In a spherical lens, especially one with a strong correction whose base curve is not in the best spherical form, such increases can significantly impact the clarity of vision in the ...

  6. Astigmatism (optical systems) - Wikipedia

    en.wikipedia.org/wiki/Astigmatism_(optical_systems)

    Astigmatism can be often corrected by glasses with a lens that has different radii of curvature in different planes (a cylindrical lens), contact lenses, or refractive surgery. [5] Astigmatism is quite common. Studies have shown that about one in three people suffers from it. [6] [7] [8] The prevalence of astigmatism increases with age. [9]

  7. PDF/A - Wikipedia

    en.wikipedia.org/wiki/PDF/A

    PDF is a standard for encoding documents in an "as printed" form that is portable between systems. However, the suitability of a PDF file for archival preservation depends on options chosen when the PDF is created: most notably, whether to embed the necessary fonts for rendering the document; whether to use encryption; and whether to preserve additional information from the original document ...

  8. History of PDF - Wikipedia

    en.wikipedia.org/wiki/History_of_PDF

    The specifications for PDF are backward inclusive. The PDF 1.7 specification includes all of the functionality previously documented in the Adobe PDF Specifications for versions 1.0 through 1.6. Where Adobe removed certain features of PDF from their standard, they are not contained in ISO 32000-1 [9] either. Some features are marked as deprecated.

  9. Comparison of e-book formats - Wikipedia

    en.wikipedia.org/wiki/Comparison_of_e-book_formats

    The .ibooks format is created with the free iBooks Author e-book layout software from Apple Inc. This proprietary format is based on the EPUB standard, with some differences in the CSS tags used in an ibooks format file, this making it incompatible with the EPUB specification. The End-User Licensing Agreement (EULA) included with iBooks Author ...