{
  "id": "terminal-csi/il",
  "family": "terminal-csi",
  "slug": "il",
  "title": "CSI IL / DL — Insert / Delete Line",
  "summary": "IL (final 'L') inserts Pn blank lines at the cursor row, scrolling lines below downward within the scroll region; DL (final 'M') deletes Pn lines at the cursor row, scrolling lines below upward. Both default Pn to 1 and operate only within the current scroll region (DECSTBM).",
  "kind": "control-sequence",
  "aliases": [
    "IL",
    "DL",
    "insert line",
    "delete line",
    "ESC [ L",
    "ESC [ M"
  ],
  "status": "standard",
  "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: CSI Ps L = Insert Ps Lines (IL); CSI Ps M = Delete Ps Lines (DL). Default Ps = 1."
    },
    {
      "claim_ref": "ext.params",
      "source_url": "https://ecma-international.org/publications-and-standards/standards/ecma-48/",
      "source_version": "ECMA-48 5th ed. 1991 (ISO/IEC 6429), clauses 8.3.67 (IL) and 8.3.32 (DL)",
      "note": "ECMA-48 defines IL (final 'L') and DL (final 'M') operating within the scroll region, default Pn 1."
    }
  ],
  "see_also": [
    "terminal-csi/ich",
    "terminal-csi/su",
    "terminal-csi/decstbm"
  ],
  "ext_type": "terminal-escape@1",
  "ext": {
    "csi_or_osc": "CSI",
    "command_number": "IL",
    "frame": {
      "introducer_7bit": "\u001b[",
      "introducer_7bit_readable": "ESC [ (0x1B 0x5B)",
      "introducer_8bit": "›",
      "introducer_8bit_readable": "0x9B (single-byte CSI, 8-bit C1)",
      "note": "CSI + single Pn + final byte: 'L' insert-line (0x4C), 'M' delete-line (0x4D). Pn defaults to 1; scoped to the scroll region."
    },
    "terminator": "none",
    "terminator_detail": {
      "note": "No string terminator; the CSI sequence ends at its final byte. Parameters Ps are decimal, ';' (0x3B) separated."
    },
    "params": [
      {
        "id": "il",
        "anchor": "#il",
        "name": "IL — Insert Line (L)",
        "meaning": "CSI Pn L inserts Pn blank lines at the cursor row; existing lines from the cursor down scroll downward within the scroll region. Blank lines take the current background color.",
        "required": true,
        "byte_sequence_ST": "\u001b[2L",
        "byte_sequence_ST_readable": "ESC [ 2 L   ==  \\x1b[2L   (insert 2 lines)",
        "subparams": []
      },
      {
        "id": "dl",
        "anchor": "#dl",
        "name": "DL — Delete Line (M)",
        "meaning": "CSI Pn M deletes Pn lines starting at the cursor row; lines below scroll upward and blank lines appear at the bottom of the scroll region.",
        "required": false,
        "byte_sequence_ST": "\u001b[2M",
        "byte_sequence_ST_readable": "ESC [ 2 M   ==  \\x1b[2M   (delete 2 lines)",
        "subparams": []
      }
    ],
    "gotchas": [
      "IL/DL operate within the current scroll region (DECSTBM); lines outside the region are not affected and do not move.",
      "DL's final byte 'M' (0x4D) is unrelated to the mouse-report 'CSI M'; context (parameters/prefix) disambiguates.",
      "Inserted/blank lines are filled with the current SGR background color.",
      "If the cursor is outside the vertical scroll region, IL/DL have no effect.",
      "Pn of 0 is treated as 1."
    ],
    "v1_smoke_test": {
      "asserts": "IL ('L') and DL ('M') render as byte-exact single-parameter CSI sequences.",
      "behavioral_conformance": "deferred to v2."
    }
  },
  "updated": "2026-05-29T00:00:00Z"
}