# 9.5 The Answer

_Peios / Peios technical reference / PSPU / File Choosing_

> The one line the chooser sends — the path chosen, or that nothing was — and what a path in each mode promises.

The chooser sends at most one answer, and ends after sending it.

| Line | Meaning |
|---|---|
| `{"type":"chosen","path":…}` | The person chose the file at `path`, an absolute path |
| `{"type":"cancelled"}` | The person chose nothing: they cancelled or closed the dialog |

## 9.5.1 What a path promises

In `open` mode, the path names a file that existed when the person chose
it. The requester opens it, and MUST handle its having gone, or changed,
since.

In `save` mode, the path names a place the person chose to write to, in
a folder that existed when they chose it. If a file was there, the
person has already said to save over it: the chooser MUST ask before it
answers with the path of a file that exists. The requester creates or
replaces the file, and MUST handle being refused, since what the person
may do can change, and the chooser could not open the file to find out.

The chooser MUST NOT open, create or change the chosen file to choose
it, and MUST NOT answer with a path it has not shown or the person has
not typed. In neither mode does a path grant anything: the requester
uses it as the person, with its own token.