> ## Documentation Index
> Fetch the complete documentation index at: https://support.floweq.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Filtering Arena Attachments

> Advanced examples for filtering which attachments get passed to Arena

The **Filter Attachments** option on the [Arena: Create Quality Process](/steps/arena/arena_create_quality) and [Arena: Update Quality Process](/steps/arena/arena_update_quality) steps lets you control which CRM attachments are eligible to pass through to Arena. This guide covers a few patterns beyond the basics.

## How the filename filter works

The filename filter is a single **regular expression**. It's matched case-insensitively, and it doesn't need to match the whole file name — it just needs to match *somewhere* in it. There's no separate "exclude" toggle or comma-separated list — both of those are done with regex, shown below.

<Tip>
  [Regex101](https://regex101.com) is a free third-party tool (not affiliated with FlowEQ) for building and testing a pattern before pasting it into the filter field. Set the flavor to "JavaScript" to match FlowEQ's behavior exactly.
</Tip>

## Example: match a simple string

To only allow files with a word somewhere in the name, e.g. `invoice`:

```
invoice
```

This matches `invoice.pdf`, `Invoice_2024.png`, `final-INVOICE-v2.docx`, etc.

## Example: match a specific file extension

To only allow PDFs, anchor the pattern to the end of the file name:

```
\.pdf$
```

The `\.` matches a literal period and `$` anchors to the end of the string, so this won't accidentally match something like `pdfnotes.txt`.

## Example: exclude a specific string

There's no built-in "exclude" option, but a negative lookahead does the same thing. To allow everything **except** files with `draft` in the name:

```
^(?!.*draft).*$
```

`(?!.*draft)` fails the match if `draft` appears anywhere in the name, so only non-matching (i.e. non-draft) file names pass the filter.

## Example: match multiple values

Use `|` (alternation) to match any of several patterns. To allow PDFs, Word docs, or images:

```
\.pdf$|\.docx?$|\.(jpe?g|png)$
```

<Note>
  If a pattern doesn't compile as a valid regular expression, Flow Builder will show "Not a valid regular expression" and block saving. If you leave the field blank, no filename filtering is applied.
</Note>