> For the complete documentation index, see [llms.txt](https://docs.coldstack.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.coldstack.io/http-api-compatible-with-amazon-s3/api-reference/common-request-headers.md). # Common request headers | Heading | Description | | ---------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `Authorization` |

Any request to ColdStack must be authorized.

Along with this heading Date, either a heading or a heading must be used x-amz-date.

Read about the authorization methods in the corresponding sections of the manual.

| | `Cache-Control` | A set of directives for caching data according to [RFC 2616](https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9) . | | `Content-​Disposition` | The name under which Object Storage will offer to save the object as a file when unloading. [RFC 2616](http://www.w3.org/Protocols/rfc2616/rfc2616-sec19.html#sec19.5.1) compliant . | | `Content-Encoding` | Defines the encoding of the content according to [RFC 2616](https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.11) . | | `Content-Length` |

The length of the request body (without headers) in accordance with RFC 2616 .

The header is required for all requests that transfer any data to Object Storage, for example, when loading an object.

| | `Content-Type` |

The data type in the request. Eg text/html. For more information about data types, see the Wikipedia article List of MIME Types .

Set by default binary/octet-stream.

| | `Content-MD5` |

128-bit MD5 hash of the request body, encoded base64.

Compliant with RFC 1864 specification .

Object Storage uses a header to ensure that the data sent matches the received data.

| | `Date` |

The date and time the request was sent.

Format: Thu, 18 Jan 2018 09:57:35 GMT.

When set x-amz-date, Object Storage ignores the header Date.

| | `Expect` |

Expected code 100-continue.

When loading data into Object Storage, an application can use the following logic:
- Send a request without a body, but with the Expect: 100-continue header set.
- Send a request with a body after receiving a response 100-continue. This request Expectshould not contain a header .

| | `Expires` | The expiration date of the answer. [RFC 2616](https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.21) compliant . | | `Host` |

The receiving host of the request.

The header is required for HTTP / 1.1, but optional for HTTP / 1.0 requests.

| | `x-amz-date` |

Date and time at the source of the request.

Format: Thu, 18 Jan 2018 09:57:35 GMT.

When set x-amz-date, Object Storage ignores the header Date.

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