{
  "id": "terminal-dec-private-mode/47",
  "family": "terminal-dec-private-mode",
  "slug": "47",
  "title": "DECSET 47 — Alternate screen buffer (legacy)",
  "summary": "CSI ? 47 h switches to the alternate screen buffer; CSI ? 47 l switches back to the normal buffer. This is the original alt-screen mode: unlike 1049 it does NOT save/restore the cursor or clear the alt buffer on entry, so it is largely superseded by 1047/1048/1049.",
  "kind": "control-sequence",
  "aliases": [
    "alternate screen",
    "alt buffer",
    "DECSET 47",
    "?47h / ?47l",
    "legacy alt screen"
  ],
  "status": "de-facto",
  "verification": "verified",
  "tier": "B",
  "source_url": "https://invisible-island.net/xterm/ctlseqs/ctlseqs.html",
  "source_version": "xterm ctlseqs, patch #410, 2026/04/19",
  "retrieved_date": "2026-05-29",
  "attribution": [
    {
      "claim_ref": "#summary",
      "source_url": "https://invisible-island.net/xterm/ctlseqs/ctlseqs.html",
      "source_version": "xterm patch #410, 2026/04/19",
      "note": "xterm ctlseqs: Ps = 4 7 -> Use Alternate Screen Buffer. (This mode is the legacy form; it does not save the cursor or clear on switch, unlike 1047/1049.)"
    }
  ],
  "see_also": [
    "terminal-dec-private-mode/1047",
    "terminal-dec-private-mode/1048",
    "terminal-dec-private-mode/1049"
  ],
  "ext_type": "terminal-escape@1",
  "ext": {
    "csi_or_osc": "DEC-private-mode",
    "command_number": 47,
    "frame": {
      "introducer_7bit": "\u001b[?",
      "introducer_7bit_readable": "ESC [ ? (0x1B 0x5B 0x3F)",
      "introducer_8bit": "›?",
      "introducer_8bit_readable": "0x9B ? (8-bit CSI + '?')",
      "note": "DEC private mode (CSI with '?' private prefix). Set = final byte 'h' (DECSET); reset = final byte 'l' (DECRST). Self-terminating."
    },
    "terminator": "none",
    "terminator_detail": {
      "note": "No string terminator: the enable/disable ends at the final byte 'h'/'l'."
    },
    "params": [
      {
        "id": "set",
        "anchor": "#set",
        "name": "Enable (DECSET)",
        "meaning": "CSI ? 47 h switches output to the alternate screen buffer (the normal buffer's contents are preserved but hidden). It does NOT save the cursor or clear the alt buffer.",
        "required": true,
        "byte_sequence_ST": "\u001b[?47h",
        "byte_sequence_ST_readable": "ESC [ ? 4 7 h   ==  \\x1b[?47h   (set / DECSET)",
        "subparams": []
      },
      {
        "id": "reset",
        "anchor": "#reset",
        "name": "Disable (DECRST)",
        "meaning": "CSI ? 47 l switches back to the normal screen buffer, revealing its preserved contents.",
        "required": true,
        "byte_sequence_ST": "\u001b[?47l",
        "byte_sequence_ST_readable": "ESC [ ? 4 7 l   ==  \\x1b[?47l   (reset / DECRST)",
        "subparams": []
      }
    ],
    "gotchas": [
      "Mode 47 is the LEGACY alt-screen: it does NOT save/restore the cursor (use 1048 for that) and does NOT clear the alt buffer on entry/exit (1047 clears on exit). Most programs should use 1049 instead, which combines save-cursor + clear + switch.",
      "Switching with 47 alone can leave stale content on the alt buffer from a previous use; clear it explicitly (CSI 2 J) if needed.",
      "Mismatched enter/leave (47 vs 1049) between a program and its children can strand you on the wrong buffer.",
      "tmux/screen track alt-screen state; mixing 47 and 1049 inside a multiplexer can confuse it.",
      "Prefer DECSET 1049 for new code; 47 exists mainly for compatibility with old programs."
    ],
    "v1_smoke_test": {
      "asserts": "Legacy alt-screen set/reset (?47h / ?47l) render as byte-exact DEC-private-mode sequences; no-save-no-clear distinction vs 1047/1049 recorded.",
      "behavioral_conformance": "deferred to v2."
    }
  },
  "updated": "2026-05-29T00:00:00Z"
}