Perspective Table

Perspective Table is an extension to the Markdown standard available in this viewer. It enables tables with multi-line block cells: nested lists, multiple paragraphs, code blocks, and images inside a single table cell. Standard Markdown tables (pipe syntax) are line-based and cannot do this.

The syntax is its own line-based notation. It is embedded as a fenced code block with the language tag perspective-table. In other Markdown applications the block remains visible as a regular code block — graceful degradation instead of broken source.

Basic syntax

A cell begins at the start of a source line with | or !. Following lines without these markers belong to the current cell. This produces multi-line cells without per-line markup.

Minimal example

Source:

```perspective-table
{|
|+ Three variants compared
|-
! Variant
! Price
|-
| Basic
| EUR 10
|-
| Premium
| EUR 50
|}
```

Result:

Extended example with lists and code block

One cell contains a nested list, another a code block. The outer fence uses four backticks so that the inner three-backtick code block remains valid.

Source:

````perspective-table
{|
|-
! Phase
! Tasks
|-
| Design
| Gather requirements:

- Clarify main structure
  - Required fields
  - Optional fields
- Layout sketch
- Stakeholder review
|-
| Build
| Code skeleton:

```bash
mkdir src
npm init -y
```
|}
````

Result:

mkdir src
npm init -y

Spans and alignment

Cells can carry attributes for spanning multiple columns or rows and for aligning cell content.

Attribute overview

Attributes appear between two pipes at the cell start: | attr="val" attr="val" | content.

Example with colspan, rowspan and align

Source:

```perspective-table
{|
|+ Effort estimate
|-
! Area
! Task
! align="right" | Hours
|-
| rowspan="2" | Design
| Gather requirements
| align="right" | 8
|-
| Layout sketch
| align="right" | 4
|-
| colspan="2" align="center" | Subtotal
| align="right" | 12
|}
```

Result:

Tips for spans and alignment

• Attributes may appear in any order: | colspan="2" align="center" | content and | align="center" colspan="2" | content are equivalent.
• Invalid values are silently ignored (e.g. colspan="abc", align="up").
• Cells without an attribute block render as normal cells.

Accessibility

Header cells (!) automatically receive the appropriate scope attribute: scope="col" for headers in the table header row, scope="row" for headers inside data rows. This lets screen readers associate data cells with their headers.

Nested tables and HTML export

Perspective tables can be nested inside each other, and a file with Perspective tables can be exported as “portable Markdown” with inline HTML tables, so it also renders as a real table in other Markdown applications.

Nested tables

A cell can itself contain a Perspective table — up to three levels deep. Important: each outer code fence must have at least one more backtick than the next inner one (CommonMark standard).

A fourth level no longer renders as a table but as a code block (depth-limit protection against pathological inputs).

Source example with two levels:

````perspective-table
{|
|+ Outer table
|-
| Effort per position
| ```perspective-table
{|
|-
! Position
! Hours
|-
| Requirements
| 8
|}
```
|}
````

Result:

HTML export for third-party Markdown renderers

.md files with Perspective tables only render as tables in this viewer. In other Markdown applications the perspective-table code block appears unchanged as source text.

Use File → More File Functions → Export → Portable Markdown… to save a variant of the file in which Perspective tables are replaced with inline HTML tables. These HTML tables render as real tables in practically any Markdown application.

• Save-As dialog with default name <basename>-portable.md in the source file’s directory. Path and name are freely editable.
• Original file stays unchanged; the export always writes to a new file.
• KaTeX formulas ($...$) in table cells are kept as formula source text on export — rendered KaTeX HTML would look broken for recipients without the KaTeX stylesheet.
• Cell attributes (colspan, rowspan, align, valign) translate to HTML standard attributes and inline styles.
• Accessibility scope on header cells is preserved.
• Nesting: up to three levels are converted recursively.
• Inline formatting in cells (bold, italic, code, links) is converted to HTML so it appears correctly in third-party renderers too.

Marker for the viewer’s display

To make the exported file also render as a table in the EM4me viewer (instead of as source text with <table> tags), the converter inserts the marker <!-- perspective-portable --> at the start of the file. The viewer detects this marker and switches the file into an HTML-capable render mode.

Security note: regular .md files still open without HTML rendering — no HTML from the Markdown is executed. Only the marker unlocks HTML rendering. For a third-party .md file carrying this marker (edge case), you must trust the source, since the HTML content there would be executed.

Sorting, status highlighting and column default

Perspective tables can be tinted with status classes per cell or row, given a default alignment per column, and made click-sortable by column header.

Status highlighting

Before a cell’s content or directly after |-, a status class can appear in dot notation:

• Cell: |.error content
• Row (applies to all cells of the row): |-.warn
• Cell status wins over row status.
• Invalid values are silently ignored.

Example:

Column-default alignment

In the table header line, cols="…" sets a default alignment per column:

• Syntax: {|+cols="left right right"
• Values are left, center or right.
• A cell with an explicit align attribute (from stage 2) overrides the default.
• For colspan no default is applied (cell spans multiple columns).

Example:

Sortable tables

+sortable in the header line makes the table click-sortable:

• Syntax: {|+sortable (combinable with cols=: {|+sortable cols="left right")
• Click on a header to sort ascending, second click descending, third click resets to original order.
• Sort heuristic: numeric first (Number() on the first line of the cell), otherwise lexicographic with locale (localeCompare, accents sorted correctly).
• Multi-line cells: sorted by the first line.
• Dates: ISO format (2026-05-19) sorts lexicographically correctly. Convert other date formats to ISO first.
• colspan/rowspan automatically disable sorting (layout risk too high).
• In portable export sorting is not included (no JavaScript in third-party Markdown renderers).

Example:

Editing via the context menu

A right-click in the block opens the Table submenu in the Editor context menu. Row operations (move, insert, delete) work on the |- sections and preserve the raw text of the cells unchanged, including attributes, status classes and multi-line content; they are always possible, even with existing spans.

Column operations and transposing move whole cell blocks (marker line plus following lines) and are only available without colspan/rowspan — with spans the column assignment would be ambiguous, so the operation is rejected with a status bar hint. When transposing, the header row becomes the first column; the cell markers (! or |) travel with their cells.

The alignment entries set the column-default alignment in the cols attribute of the {| line (see the “Column-default alignment” section); columns without a setting receive the placeholder -, and the align attributes of individual cells stay untouched.

Tips

|- is required between table rows. Without |- any following | cells are interpreted as additional cells in the same row, not a new row. Most common beginner pitfall.

Four-backtick outer fence whenever a cell contains a three-backtick code block. Otherwise the inner code block prematurely closes the outer fence.

One cell per source line start. Following lines without leading |, !, |- or |} belong to the current cell.

Whitespace at the start and end of a cell is stripped when rendered. List indentation inside the cell is preserved.

Inline formatting, wiki links, and images work in cells like anywhere else (**bold**, *italic*, `code`, [[Wiki link]], ![alt](image.png)).

Portability

.md files with perspective-table blocks only render as tables in this viewer. In other Markdown applications the block appears as a regular code block. This is a deliberate design choice, not a bug — content stays readable everywhere instead of becoming syntactically broken source.

Feature status

The planned feature set of Perspective tables is now complete: basic syntax, spans and alignment, nesting and HTML export, sorting, status highlighting and column default, as well as the editing operations via the context menu.