> ## Documentation Index > Fetch the complete documentation index at: https://openrouter.ai/docs/llms.txt > Use this file to discover all available pages before exploring further. # ContentFilterEntry A custom regex content filter that scans request messages for matching patterns. ## Fields | Field | Type | Required | Description | Example | | --------- | ----------------------------------------------------------------------- | -------------------- | --------------------------------------------------------------- | -------------------------- | | `action` | [components.ContentFilterAction](../components/contentfilteraction.mdx) | :heavy\_check\_mark: | Action taken when the pattern matches | block | | `label` | *OptionalNullable\[str]* | :heavy\_minus\_sign: | Optional label used in redaction placeholders or error messages | \[API\_KEY] | | `pattern` | *str* | :heavy\_check\_mark: | A regex pattern to match against request content | \b(sk-\[a-zA-Z0-9]\{48})\b |