The first control along the top decides what one row means:

• Notes: one row per note, with its frontmatter properties and a few counts Header works out from the text (decisions, questions, open loops, open tasks, words).
• Tasks: one row per checkbox line, from every note. Each task carries its note's properties, so “tasks in notes where client is Acme” works. For how to write due dates, see Tasks.
• Blocks: one row per paragraph, list item, quote or heading that carries an inline tag. A line like Walked at lunch #gratitude becomes a row.
• Captures: one row per entry you saved with Quick Capture or the other capture tools (see Capturing ideas).

Next to it, pick a time range: All Time, Today, This Week or This Month. The range means something slightly different for each kind of row:

Blocks in more detail

With Blocks selected, a row of tag chips appears under the controls, most-used tag first. Click a chip to show only that tag; click it again to clear it. A parent tag also matches its children, so #project finds lines tagged #project/header.

Each block gets a date: a date written in the line itself, otherwise the date in a daily note's filename, otherwise the day the note was last changed. That way a journal line lands on the day it was about. Notes Header generated from other notes (lens syntheses, Atlas pages, saved Ask Header answers) are left out, so a tagged line appears once. Double-click a block row to open its note at that line.

The row of small icons at the top right switches the shape. The shape is saved with the lens.

Click Add Filter to add a condition on a property or one of the counts. Each filter is a key, a test (is, is not, contains, >, <, has any value, is empty) and a value. With two or more filters, choose All (every filter must match) or Any (one is enough). The Filter rows box at the right is a quick text search over what's showing; it isn't saved with the lens.

View options opens a small panel with:

• Folder: only rows under this folder. Leave it empty for the whole vault.
• Columns (notes and captures): tick properties and counts to show. Columns that are empty for every visible row are hidden; the footer tells you how many and lets you show them.
• Group (notes and captures): pick a property and the lens switches to a Board with one column per value. The button then reads, for example, Board: status.
• Sort: pick a key; pick it again to flip the order.
• Set Property…: appears when you've selected notes (see below).

The footer under the rows counts what's showing. For note lenses it also adds a total (Σ) and an average (x̄) for any column holding numbers, such as fee or words.

Open the lens menu (the button with the lens name) and choose New from Template. The templates are ordinary lenses you can change afterwards:

New from Question AI

Click New from Question, describe the lens in a sentence, and click Compile Lens. For example: “client notes with fee over 5000, this month”. The AI writes the filters; Header checks them against the properties your vault really has and runs the lens itself. If the AI used a property your vault doesn't have, Header drops it and tells you which one.

Only your sentence and the names of your properties go to the AI, not your notes. It uses Apple Intelligence when it's available on your Mac, otherwise the AI provider you set up in Settings → AI. Check the filters it produced before you save.

While a lens has unsaved changes, its menu reads Unsaved lens •. Click Save, give it a name the first time, and it appears in the lens menu from then on. After that, Save updates it. Choose Rename… from the lens menu to rename a saved lens, or click Delete to remove it. Deleting a lens doesn't touch any notes.

Saved lenses are stored in the vault, in .header/views.json, so they go wherever the vault goes. Renaming a lens also updates any Base Note that shows it (see below), so those dashboards keep working. Header saves the open note first; if it can't, it asks you to save the note before renaming.

In the Table shape, click a row and ⌘-click or ⇧-click to add more. In the List, Timeline, Folders and Calendar shapes, each note row has a checkbox for selecting it. Task rows have a checkbox too, but that one ticks the task off; to select tasks, use the Table shape.

Every action in More works on the selected rows. With nothing selected, it works on everything visible, and the menu items say Visible Results. When rows are selected the button reads More (3) and the items say Selected. The menu holds:

• Create Synthesis Note… and Create Index Note… (see below).
• Save as Base Note (live dashboard)…
• Copy Note Links: copies a [[link]] to each row's note, one per line.
• Select All Visible or Deselect all.
• Export as CSV…, TSV…, Markdown Table… or JSON…, and matching Copy as items for the clipboard. The export has the columns Date, Kind, Title, Source, Words, Loops, Decisions and Questions.
• Refresh from Index: reloads the rows if you think something is missing.

Right-click a row for Open in Editor, Reveal in Finder, Copy Note Link, Copy Relative Path and Star. Double-click a row to open it.

Click Ask This Lens to open Ask Header with its scope set to the rows in front of you (or only the selected ones). Ask something like “Which of these client meetings ended without a next step?” and the answer draws on those notes, with sources you can check. Notes Header generated, such as earlier syntheses, are left out so the answer rests on your own writing. How answers and providers work is covered in Ask Header.

Both actions build a new Markdown note from the rows, with no AI involved. They differ in how much they copy in:

Before anything is written, a review sheet shows the exact Markdown and where it will go: a Folder (Lens Notes by default) and a Filename built from the lens and today's date. Change either, then click Create Note. If the name is taken, Header picks a new one and says so; it won't overwrite an existing file. Afterwards you can Open Note, Reveal in Finder or Copy Link.

The source notes are not modified. The new note's frontmatter records the lens, the query and how many rows and sources it came from.

Save as Base Note (live dashboard)… saves the lens, writes a note named after it into a Dashboards folder, and opens it. The note holds a small header-lens block that names the lens and a row limit (50). In Header the block shows the lens's rows and updates as your vault changes; to change what it shows, edit the lens in Lenses. In Obsidian and other editors, the block appears as plain code.

The lens needs a name first, and the name can't match another saved lens. Unlike an index or synthesis note, a Base Note is live rather than a snapshot.