> ## 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](../../models/components/contentfilteraction.mdx) | :heavy\_check\_mark: | Action taken when the pattern matches | block | | `Label` | optionalnullable.OptionalNullable\[`string`] | :heavy\_minus\_sign: | Optional label used in redaction placeholders or error messages | \[API\_KEY] | | `Pattern` | `string` | :heavy\_check\_mark: | A regex pattern to match against request content | \b(sk-\[a-zA-Z0-9]\{48})\b |