"Confirm file format conversion on open" option can also assist by warning a document being opened is in a format that does not match the format implied by the file's extension, and giving the option to abort opening that file. One exploit attacking a vulnerability was patched in Microsoft Word in April 2015. Since 2014 there have been malware RTF files embedding OpenXML exploits. Implementations Each RTF implementation usually implements only some versions or subsets of the RTF specification. Many of the available RTF converters cannot understand all new features in the latest RTF specifications. The WordPad editor in Microsoft Windows creates RTF files by default. It once defaulted to the Microsoft Word 6.0 file format, but write support for Word documents (.doc) was dropped in a security update. Read support was also dropped in Windows 7. WordPad does not support some RTF features, such as headers and footers. However, WordPad can read and save many RTF features that it cannot create, including tables, strikeout, superscript, subscript, "extra" colors, text background colors, numbered lists, right or left indent, quasi-hypertext and URL linking, and various line spacings. RTF is also the data format for "rich text controls" in MS Windows APIs. The default text editor for macOS, TextEdit, can also view, edit and save RTF files as well as RTFD files, and uses the format as its default. As of July 2009, TextEdit has limited ability to edit RTF document margins. Much older Mac word processing application programs such as MacWrite and WriteNow had the same RTF abilities as TextEdit has. The free and open-source word processors AbiWord, Apache OpenOffice, Bean, Calligra, KWord, LibreOffice and NeoOffice can view, edit and save RTF files. The RTF format is also used in the Ted word processor. Scrivener uses individual RTF files for all the text files that make up a given "project". SIL International’s freeware application for developing and publishing dictionaries uses RTF as its most common form of document output. RTF files produced by Toolbox are designed to be used in Microsoft Word, but can also be used by other RTF-aware word processors. RTF can be used on some ebook readers because of its interoperability, simplicity and low CPU processing requirements. Libraries and converters The open-source script rtf2xml can partially convert RTF to XML. GNU UnRTF is an open-source program to convert RTF into HTML, LaTeX, troff macros and other formats. pyth