Writer is capable of opening and saving documents in a number of formats, including the OpenDocument (ODT is its default format), Microsoft Word's DOC, DOCX, RTF and XHTML.[6] A spelling and grammar checker (Hunspell)[7][8] Built-in drawing tools Built-in calculation functions Built-in equation editor[9] Export in PDF format, generate hybrid PDF (embedded ODF), create fillable PDF form The ability to import and edit PDF files.[10] Ability to edit HTML, XHTML files visually without using code with WYSIWYG support Export in HTML, XHTML, XML formats Export in EPUB ebook format Contents, index, bibliography Signing documents, encryption Change tracking during revisions, compare two documents Database integration, including a bibliography database MailMerge[11] Scriptable and Remote Controllable via the UNO API Open Type stylistic sets and character variants of fonts are not selectable from the menus, but can be specified manually in the font window.