# Make and undo an explicit byte edit

Replace one byte, restore the original buffer and download its exact binary contents.

Source: https://help.smartfact.ai/octetbench/guides/edit-bytes

Audience: Operator

Replace one byte, restore the original buffer and download its exact binary contents. This is isolated practice with invented records. Nothing is uploaded or written into a live system.

## Make and undo an explicit byte edit

1. **Choose hexadecimal input**

   Choose hexadecimal input.

   Hexadecimal describes the bytes directly, without relying on a pasted line ending.

2. **Enter UTF-8 and line-ending bytes**

   Enter UTF-8 and line-ending bytes.

   These bytes contain A, the two-byte character é, a carriage return and a line feed.

3. **Apply the exact bytes**

   Apply the exact bytes.

   Apply checks the complete input before replacing the current buffer. The five bytes remain available in every supported view.

4. **Enter one replacement byte**

   Enter one replacement byte.

   At offset zero, 42 is hexadecimal for B. This is a deliberate edit to one byte, not a text repair.

5. **Replace the selected byte**

   Replace the selected byte.

   The current buffer now begins with B. The staged hex input is updated, and Undo can restore the earlier bytes.

6. **Undo the byte edit**

   Undo the byte edit.

   Undo restores the exact prior buffer. It does not re-encode the source text.

7. **Download the raw bytes**

   Download the raw bytes.

   The binary download contains the current bytes exactly, including both line-ending bytes.

[Watch or practise this chapter](https://help.smartfact.ai/octetbench/demo?guide=edit-bytes&chapter=edit-bytes&audience=office)

Review the result and its limits before using it in another application.