.APT File Extension
What is an APT file?
Text document written in Almost Plain Text (APT), a simple markup language that describes the formatting of a text document; can be converted to HTML, PDF, PostScript, RTF, or other formats using a document generation program such as Aptconvert, which is often used with Maven software development tools.
You can edit APT files with any text editor since the files are saved in a plain text format.
NOTE: APT files are similar to Wiki webpages, which are also written in a simple markup language intended to be displayed as HTML.