StoryMill is a text editor

Text editor

A text editor is a type of program used for editing plain text files.Text editors are often provided with operating systems or software development packages, and can be used to change configuration files and programming language source code....

 designed for fiction

Fiction

Fiction is the form of any narrative or informative work that deals, in part or in whole, with information or events that are not factual, but rather, imaginary—that is, invented by the author. Although fiction describes a major branch of literary work, it may also refer to theatrical,...

 writer

Writer

A writer is a person who produces literature, such as novels, short stories, plays, screenplays, poetry, or other literary art. Skilled writers are able to use language to portray ideas and images....

s. It provides scene, chapter and character

Character (arts)

A character is the representation of a person in a narrative work of art . Derived from the ancient Greek word kharaktêr , the earliest use in English, in this sense, dates from the Restoration, although it became widely used after its appearance in Tom Jones in 1749. From this, the sense of...

 management capabilities along with the ability to annotate text and a claimed industry-first timeline view.

Avenir was developed by Todd Ransom, of Return Self Software, who also developed Montage

Montage (software)

Montage is screenwriting software developed for Mac OS X. Montage allows the creation, editing, and management of screenplays on Macintosh computers. Montage can import Final Draft documents...

, a Mac screenwriting application, for Mariner Software

Mariner Software

Mariner Software is an American corporation with a focus on designing and publishing computer software products. Headquartered in Minneapolis, Minnesota, Mariner develops, sells, and supports professional and personal software for the productivity, writing and creative markets...

. From version 3, Avenir is being "republished" by Mariner, as StoryMill.