diff --git a/notebook/editor.neovim.folds.org b/notebook/editor.neovim.folds.org
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+:PROPERTIES:
+:ID:       73bca39f-e492-47aa-92e7-629d3b8b92ad
+:END:
+#+title: Neovim folds
+#+date: 2022-04-03 16:59:05 +08:00
+#+date_modified: 2022-04-03 16:59:24 +08:00
+#+language: en
+
+
+- it is a built-in feature in Neovim;
+  enables you to quickly navigate a long document by hiding them and opening them when you want
+- some keybindings for managing folds
+  | Keymap | Description                |
+  |--------+----------------------------|
+  | ~zf~   | Create a fold.             |
+  | ~zA~   | Toggle a fold recursively. |
+  | ~zM~   | Close all folds.           |
+  | ~zR~   | Open all folds.            |
+  | ~zj~   | Move one fold down.        |
+  | ~zk~   | Move one fold up.          |
+- while in insert mode, there are no folds under your cursor so you can see what you type
+- while manually managing folds can be tedious, Neovim does have a way to automatically manage folds for you;
+  this is dictated through the ~foldmethod~ variable;
+  for more information for the following methods, see ~fold-${VALUE}~ with the [[id:0a0fe63e-dcf3-4928-9e82-5513784c1244][Neovim help system]]
+  - with ~manual~ value, no additional actions are done
+  - with ~marker~ value, a fold will be created ala-HTML markers
+  - with ~expr~ value, a fold will be managed through its fold level evaluated from ~foldexpr~ function;
+    certain tools like [[https://github.com/nvim-treesitter/nvim-treesitter][nvim-treesitter]] takes advantage of this to arrange the code through its blocks, scope, etc.
diff --git a/notebook/editor.neovim.help-system.org b/notebook/editor.neovim.help-system.org
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+:PROPERTIES:
+:ID:       0a0fe63e-dcf3-4928-9e82-5513784c1244
+:END:
+#+title: Neovim help system
+#+date: 2022-04-01 16:20:55 +08:00
+#+date_modified: 2022-04-03 16:59:48 +08:00
+#+language: en
+
+
+- the main command is ~:h~ which should open ~help.txt~ if given no arguments;
+  this should be enough if you want to explore much of Neovim itself as the document has
+- if given an argument, Vim will open the section of the document with the closest match
+- some points of interest
+  - you can view the complete listing of help tags with ~help-tags~
+  - there is also a index of tags from ~index.txt~
diff --git a/notebook/editor.neovim.text-objects.org b/notebook/editor.neovim.text-objects.org
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+:PROPERTIES:
+:ID:       5c4641ab-91d5-4cd6-bdec-4f899fdd9ea5
+:END:
+#+title: Neovim text objects
+#+date: 2022-04-01 16:06:02 +08:00
+#+date_modified: 2022-04-02 19:35:33 +08:00
+#+language: en
+
+
+(Neo)Vim has a bunch of text objects that are beyond simple boundaries other than a word (~aw~, ~aW~).
+You can find more of them with ~text-objects~ section from [[id:0a0fe63e-dcf3-4928-9e82-5513784c1244][Neovim help system]].
+
+| Text object | Description                     |
+|-------------+---------------------------------|
+| ~ap~        | A paragraph, equivalent to ~}~. |
+| ~as~        | A sentence, equivalent to ~)~.  |
+| ~ab~        | A '( )' block.                  |
+| ~aB~        | A '{ }' block.                  |
+
+There is also a variation for selecting only the inner content of the previous text objects (e.g., ~ip~ for the inner paragraph, ~is~ for inner sentence) with the whitespace removed.
+
+Note that selecting with text objects is different from selecting with [[roam:Neovim motions]] where it refers to the current position up to the end of the next selection.
+Meanwhile, text objects selection will select to the referred object as a whole no matter where the cursor position.
+For example, selecting with the paragraph (i.e., ~vap~) will select the whole paragraph where the cursor rests.
+
+Aside from the built-in text objects, you can create your own.
+Which also means others have created some custom text objects.
+
+- [[https://github.com/nvim-treesitter/nvim-treesitter-textobjects][nvim-treesitter-textobjects]] add text objects support for selecting (and swapping, moving, and peeking) tree-sitter nodes.
+  (Assuming you have tree-sitter support enabled for Neovim.)