From 139d8ea2080c999fe9125b1bc4f8b7acf4c58335 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Fri, 6 Oct 2023 14:27:51 -0700
Subject: [PATCH] website: ind

---
 website/app/vt/cud/page.mdx |   1 -
 website/app/vt/ind/page.mdx | 117 ++++++++++++++++++++++++++++++++++++
 website/app/vt/lf/page.mdx  |   9 +++
 3 files changed, 126 insertions(+), 1 deletion(-)
 create mode 100644 website/app/vt/ind/page.mdx
 create mode 100644 website/app/vt/lf/page.mdx

diff --git a/website/app/vt/cud/page.mdx b/website/app/vt/cud/page.mdx
index 10ad7d493..63c51c562 100644
--- a/website/app/vt/cud/page.mdx
+++ b/website/app/vt/cud/page.mdx
@@ -73,4 +73,3 @@ printf "X"
 |__________|
 |_Xc_______|
 ```
-
diff --git a/website/app/vt/ind/page.mdx b/website/app/vt/ind/page.mdx
new file mode 100644
index 000000000..621295abd
--- /dev/null
+++ b/website/app/vt/ind/page.mdx
@@ -0,0 +1,117 @@
+import VTSequence from "@/components/VTSequence";
+
+# Index (IND)
+
+<VTSequence sequence={["ESC", "D"]} />
+
+Move the cursor down one cell, scrolling if necessary.
+
+This sequence always unsets the pending wrap state.
+
+If the cursor is exactly on the bottom margin and is at or within the
+[left](#TODO) and [right margin](#TODO), [scroll up](#TODO) one line.
+If the scroll region is the full terminal screen and the terminal is on
+the [primary screen](#TODO), this may create scrollback. See the
+[scroll](#TODO) documentation for more details.
+
+If the cursor is outside of the scroll region or not on the bottom
+margin of the scroll region, perform the [cursor down](/vt/cud) operation with
+`n = 1`.
+
+This sequence will only scroll when the cursor is exactly on the bottom
+margin and within the remaining scroll region. If the cursor is outside
+the scroll region and on the bottom line of the terminal, the cursor
+does not move.
+
+## Validation
+
+### IND V-1: No Scroll Region, Top of Screen
+
+```bash
+printf "\033[1;1H" # move to top-left
+printf "\033[0J" # clear screen
+printf "A"
+printf "\033D" # index
+printf "X"
+```
+
+```
+|A_________|
+|_Xc_______|
+```
+
+### IND V-2: Bottom of Primary Screen
+
+```bash
+lines=$(tput lines)
+printf "\033[1;1H" # move to top-left
+printf "\033[0J" # clear screen
+printf "\033[${lines};1H" # move to bottom-left
+printf "A"
+printf "\033D" # index
+printf "X"
+```
+
+```
+|A_________|
+|_Xc_______|
+```
+
+### IND V-3: Inside Scroll Region
+
+```bash
+printf "\033[1;1H" # move to top-left
+printf "\033[0J" # clear screen
+printf "\033[1;3r" # scroll region
+printf "A"
+printf "\033D" # index
+printf "X"
+```
+
+```
+|A_________|
+|_Xc_______|
+```
+
+### IND V-4: Bottom of Scroll Region
+
+```bash
+printf "\033[1;1H" # move to top-left
+printf "\033[0J" # clear screen
+printf "\033[1;3r" # scroll region
+printf "\033[4;1H" # below scroll region
+printf "B"
+printf "\033[3;1H" # move to last row of region
+printf "A"
+printf "\033D" # index
+printf "X"
+```
+
+```
+|__________|
+|A_________|
+|_Xc_______|
+|B_________|
+```
+
+### IND V-5: Bottom of Primary Screen with Scroll Region
+
+```bash
+lines=$(tput lines)
+printf "\033[1;1H" # move to top-left
+printf "\033[0J" # clear screen
+printf "\033[1;3r" # scroll region
+printf "\033[3;1H" # move to last row of region
+printf "A"
+printf "\033[${lines};1H" # move to bottom-left
+printf "\033D" # index
+printf "X"
+```
+
+```
+|__________|
+|__________|
+|A_________|
+|__________|
+|Xc________|
+```
diff --git a/website/app/vt/lf/page.mdx b/website/app/vt/lf/page.mdx
new file mode 100644
index 000000000..10ac27bbb
--- /dev/null
+++ b/website/app/vt/lf/page.mdx
@@ -0,0 +1,9 @@
+import VTSequence from "@/components/VTSequence";
+
+# Linefeed (LF)
+
+<VTSequence sequence="LF" />
+
+This is an alias for [index (IND)](/vt/ind).
+
+TODO: linefeed mode