# Extend the end: Guidelines

> Guidelines for assigning identifiers to the end of an ID in a Johnny.Decimal system.

## Usage considerations

Extending the end is for when you have an ID that needs to be repeated in some way.

Of the three system expansion strategies, creating a child ID to extend the end is the simplest and therefore most preferred.

As well as extending an ID it can be used to link JDex child notes back to a parent note.

## Recording child notes

Traditionally, each of your IDs has a single JDex entry: it is this entry that defines the ID. But one note can get long and become difficult to manage.

To create child notes, just use the `+` after the ID in the note title.

For example, I needed to record a long transaction history for a lawnmower warranty return. `13.41 Purchase receipts` is the home for this, but I didn't want to clutter the parent note.

I created a child note, `13.41+ Ozito mower`. This note is an instance of `13.41`, and the `+` makes it sort below the parent note.

![Screenshot of Bear, showing the two notes as described below.](https://johnnydecimal.com/documentation/62.29A-Bear_Ozito--light-680x290@2x.png)

_Figure 62.29A. Two Bear notes with the same ID. 13.41 is the parent note. 13.41+ is a child note that sorts below it._

## Your filesystem

The child ID can be thought of as a filesystem subfolder. You might choose to keep 'primary' items in the ID folder and create subfolders for each child ID. Or you might find it neater to keep _everything_ in subfolders.

Regardless, if you create a subfolder for an extended item, name it with the `+`, e.g. `+ Wendy`. This signals to you that this folder is special: it isn't just some subfolder you've created. It has a JDex entry.

These folders will also sort above all other subfolders.

```text
11.63 Veterinary care
├──── 2022-03-21 General chicken care.pdf
├──── + Belinda/
│     └── 2023-02-14 Wing x-ray.png
├──── + Marie/
│     └── 2024-07-08 Beak clip.pdf
└──── + Wendy/
        └── 2023-08-11 Sore eye.pdf
```

_Figure 62.29B. General chicken care is stored in 11.63. Each chicken's files are stored in named subfolders._