Terminal SGR Background Color Token

Description

Format an explicit 0–255 indexed SGR background color field; no RGB palette mapping or terminal display guarantee.

Terminal escape sequences can encode cursor commands, text styles and other controls inside ordinary text. SGR changes selected graphic attributes; CSI and OSC tokens have different framing. These tools operate on explicit strings and records, with a deliberately limited parser or style model rather than an emulated screen.^[1]

Format an explicit 0–255 indexed SGR background color field; no RGB palette mapping or terminal display guarantee.

When to use this tool

Use this tool to format an explicit 0–255 indexed SGR background color field; no RGB palette mapping or terminal display guarantee.

How to use the tool and how it works

Enter index using the field definitions below.
Run the operation. Correct input errors before interpreting an output.
Read result.parameters, result.token. Use the ordering, boundary rules and absence conditions described below.

Validate a palette index from 0 through 255 and return parameters [48, 5, index] together with their SGR token.^[2]

Input field	Meaning and units	Accepted input
index	Palette index, an integer 0–255.	A finite safe integer within the operation’s stated bounds.

Output field	Interpretation
result	Object containing the named fields below.
result.parameters	Numeric SGR parameter sequence in the stated order.
result.token	Formatted terminal control string; JSON escaping shows its control characters.

json

{
  "input": {
    "index": 200
  },
  "output": {
    "result": {
      "parameters": [
        48,
        5,
        200
      ],
      "token": "\u001b[48;5;200m"
    }
  }
}

Limitations and assumptions

This selects background palette color without resolving the terminal’s palette.
Source spans use zero-based UTF-16 offsets with exclusive ends; byte totals, where returned, use UTF-8. Escape tokens are represented as JSON escapes in the example and are not executed by this description.
Every declared top-level input field is required and unexpected fields are rejected. Ordinary strings are limited to 8,192 UTF-16 code units and lists to 128 entries, with tighter operation-specific bounds where stated. JSON text has bounded nesting and node counts.
Numeric outputs must be finite and no larger in absolute magnitude than the safe-integer limit; operations returning exact large integers use decimal text. Positions are zero-based and spans end exclusively unless the operation explicitly states a different convention.

Alternative or Complementary methods

Use token inspection for source offsets and style replay for the supported attributes. A real terminal emulator is needed to determine screen contents, terminal-specific rendering or device behavior.

References

ECMA-48: Control Functions for Coded Character Sets — Ecma International
Tool behavior and example: Terminal SGR Background Color Token — tool.io

Similar or alternative tools

Terminal SGR Foreground Color Token
Format an explicit 0–255 indexed SGR foreground color field; no RGB palette mapping or terminal display guarantee.
Terminal SGR Indexed Color Field Parser
Parse exactly one SGR 38/48;5;n indexed color field, not an arbitrary SGR stream or terminal palette lookup.