geml-spec Writing GEML — one-page cheatsheet
GEML is plain text. Every structured thing is one typed block:
=== <type> {#id .class key=val}
<body>
===
The opening fence is ≥ 3 =. The closing fence must be the same length.
To nest a block inside a block, make the outer fence longer:
==== note
Example code:
=== code {lang=python}
print("hi")
===
====
Easier — close by name. Give a block an #id and close it with === #id.
That closes by name, not by length, so you can nest with all === fences and
never miscount:
=== note {#ex}
Example code:
=== code {#snippet lang=python}
print("hi")
=== #snippet
=== #ex
Body modes: code / diagram / math / table / embed are raw;
note are parsed prose; meta is one key=val per line.
Metadata
=== meta
title = "My doc"
version = 0.1
===
In prose, {{title}} inserts a meta value (an unknown key is a build error).
Headings & lists (ATX only)
# Title ## Section {#explicit-id}
- bullet 1. ordered
- nested by indentation (2 spaces)
- [ ] task - [x] done
Inline
*em* **strong** `code` ~~strike~~ $a^2$ (inline math)
[text](https://x) [text](#id) [[#id]] (auto text) [^note] 
A reference to a missing id is a build error. Define a footnote with
a note block (e.g. === note {#note}), then cite it inline with [^note].
Tables
=== table {#fy caption="Sales" format=csv header=1}
Seg, Q1, Q2, Q3, Q4
Cloud, 1, 2, 3, 4
===
=== view {#fy-report src=#fy compute="FY [%.1f] = Q1 + Q2 + Q3 + Q4" summary="Seg = 'Total'; Q1 = sum(Q1); FY = sum(FY)"}
===
- A
tableholds FACTS.compute/summary— andwhere/order/limit/select/by/aggregate— belong to aviewwhosesrc=names the table. - The attribute object
{…}is one physical line (don't wrap it). compute:Name = exprover+ - * / ( ), columns by header name (quote names with spaces:'Unit Price') or letterA,B,…;;-separate multiple formulas;[%.1f]sets number display.summary: one foot row; each cell is a literal ('Total') or an aggregate expression oversum/avg/min/max/count. A bare (non-aggregated) column is an error.- Visual form also works:
| a | b |rows with a|---|separator.
Diagrams & charts
=== diagram {#flow format=mermaid caption="Flow"}
graph LR
A --> B
===
Chart drawn from a table or a view (empty body — the spec is in the attributes):
=== diagram {format=geml-chart data=#fy-report type=bar x=Seg y=FY}
===
type ∈ bar|line|area|pie|scatter; x/y are column names; data=#id must
point at a table, a view, or a record-array data block — a computed column
like FY exists only on the view, so bind there; a typo'd column or dangling
id is a build error.
Math
=== math {#g caption="Gaussian"}
\int_{-\infty}^{\infty} e^{-x^2} dx = \sqrt{\pi}
===
Things that are build ERRORS — avoid them
- A reference / footnote / chart column /
{{meta}}key that does not resolve. - A duplicate
#id. - A block not closed by an equal-length fence (when nesting, the outer fence must be longer than any fence inside it).
- A
summarycell using a column that isn't wrapped in an aggregate. - Raw HTML (there is none in GEML).